NAME

sloane - lookup integer sequences, OEIS A-numbers, etc.

SYNOPSIS

sloane [-n N] [--all] [--oeis] TERMS...
sloane [--invert] --filter
sloane (--update|--version|--help)

DESCRIPTION

sloane provides a command line interface to Sloane's OEIS (The On-Line Encyclopedia of Integer Sequences). It can be used offline (the default) as well as online (with the --oeis option). The first time sloane is used in offline mode the user will be asked to run sloane --update. This will download https://oeis.org/{names.gz,stripped.gz} and unpack them into .oeis-data/{names,stripped} in the home directory. Alternatively, one can do this by hand using wget and gunzip, say, if prefered.

A common way to use sloane is to search for entries matching a sequence of consecutive terms:

sloane 1,3,19,183,2371,38703

At the time of writing this would return

{
  "trail": ["{1,3,19,183,2371,38703}"],
  "hops": "A006531",
  "name": "Semiorders on n elements.",
  "seq": [1,1,3,19,183,2371,38703,763099,17648823,468603091,...]
}

The --filter option can be very useful when checking a large number of sequences. In this mode sloane expects input in the form returned by hops(1). It reads standard input line-by-line, if the sequence in the right hand side of the entry read is in the local database, then the entry is returned to standard output; if not, it is ignored. This way one can quickly filter out the sequences from the input that are in the local database. To also lookup the names of those sequences one could run

sloane --filter <FILE | sloane

If the sequences one wishes to filter are not already in form returned by hops then one may mold them into that form using hops --tag. See the EXAMPLES section for more usage examples.

OPTIONS

--oeis

Online search; lookup the provided terms in Sloane's On-Line Encyclopedia of Integer Sequences (OEIS).

-n N

Fetch at most this many entries (default: 5).

--all

Fetch all matching entries (equivalent to -n 999999).

--filter

Filter out those sequences from standard input that are in the local database. The input is expected to be in the form returned by hops(1).

--invert

Return sequences not in the database (used with --filter).

--update

Update the local database.

--version

Print version information.

--help

Briefly describe the available options.

EXAMPLES

Lookup A-numbers:

$ sloane A000111 A000112
{
  "hops": "A000111",
  "name": "Euler or up/down numbers: e.g.f. sec(x) + tan(x)...",
  "seq": [1,1,1,2,5,16,61,272,1385,7936,50521,353792,2702765,22368256,...]
}
{
  "hops": "A000112",
  "name": "Number of partially ordered sets (\"posets\") with n unlabeled elements.",
  "seq": [1,1,2,5,16,63,318,2045,16999,183231,2567284,46749427,...]
}

Lookup a sequence (limit to at most two results):

$ sloane -n2 1,1,2,5,15,52,203,877,4140,21147,115975,678570
{
  "trail": ["{1,1,2,5,15,52,203,877,4140,21147,115975,678570}"],
  "hops": "A000110",
  "name": "Bell or exponential numbers: number of ways to partition a set of n...",
  "seq": [1,1,2,5,15,52,203,877,4140,21147,115975,678570,4213597,27644437,...]
}
{
  "trail": ["{1,1,2,5,15,52,203,877,4140,21147,115975,678570}"],
  "hops": "A192127",
  "name": "Number of set partitions of {1, ..., n} that avoid 6-nestings.",
  "seq": [1,1,2,5,15,52,203,877,4140,21147,115975,678570,4213596,27644383,...]
}

Lookup a sequence generated by hops(1):

$ hops 'y=1+integral(2*y^2-y);laplace(y)' | sloane
{
  "trail":["y=1+integral(2*y^2-y);laplace(y)"],
  "hops":"A000670",
  "name":"Fubini numbers: number of preferential arrangements of n labeled ...",
  "seq":[1,1,3,13,75,541,4683,47293,545835,7087261,102247563,1622632573,...]
}
{
  "trail":["y=1+integral(2*y^2-y);laplace(y)"],
  "hops":"A034172","name":"Nearest integer to n!/(2*log(2)^(n+1)).",
  "seq":[1,1,3,13,75,541,4683,47293,545835,7087261,102247563,1622632573,...]
}

Fetch the OEIS entry whose A-number is A006531:

sloane --oeis id:A006531

Return at most 3 results of a free text search:

sloane -n 3 --oeis "(2+2)-free posets"

NOTES

Please use the --oeis option with some moderation as not to overburden the OEIS-server; see OEIS' policy on searching the database.

SEE ALSO

hops(1) http://akc.is/hops
Source code for sloane: http://akc.is/sloane

AUTHOR

Anders Claesson http://akc.is