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


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


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{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.


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).
Fetch all matching entries (equivalent to -n 999999).
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).
Return sequences not in the database (used with --filter).
Update the local database.
Print version information.
Briefly describe the available options.


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
  "name":"Fubini numbers: number of preferential arrangements of n labeled ...",
  "hops":"A034172","name":"Nearest integer to n!/(2*log(2)^(n+1)).",

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"


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


Source code for sloane:


Anders Claesson