# sloane

A command line interface to Sloane's On-Line Encyclopedia of Integer Sequences (OEIS)

## Install

```
$ cabal install sloane
```

## Usage

```
$ sloane --help
Search Sloane's On-Line Encyclopedia of Integer Sequences
sloane [OPTIONS] SEARCH-TERMS
Common flags:
-k --keys=KEYS Keys of fields to print (default: SN)
-a --all Print all fields
-u --url Only print urls of found entries
-n --limit=INT Limit the number of entries retrieved (default: 5)
-? --help Display help message
-V --version Print version information
```

## Examples

Search for entries matching a sequence:

```
$ sloane 1,3,19,183,2371,38703
S A006531 1,1,3,19,183,2371,38703,763099,17648823,468603091,14050842303,
N A006531 Semiorders on n elements.
```

Show the sequence, name, comments, and formula fields of the sequence whose A-number is A006531:

```
$ sloane -kSNCF id:A006531
S A006531 1,1,3,19,183,2371,38703,763099,17648823,468603091,14050842303,
N A006531 Semiorders on n elements.
C A006531 Labeled semiorders on n elements: (1+3) and (2+2)-free posets. - Detlef Pauly (dettodet(AT)yahoo.de), Dec 27 2002
F A006531 O.g.f.: Sum_{n>=1} (2*n)!/(n+1)! * x^n / Product_{k=0..n} (1+k*x). [From Paul D. Hanna, Jul 20 2011]
F A006531 E.g.f.: C(1-exp(-x)), where C(x) = (1 - sqrt(1 - 4*x)) / (2*x) is the ordinary g.f. for the Catalan numbers A000108.
F A006531 a(n) = sum( S(n, k) * k! * M(k-1), k=1..n), S(n, k): Stirling number of the second kind, M(n): Motzkin number, A001006. - Detlef Pauly, Jun 06 2002
```

Return at most 3 results of a free text search:

```
$ sloane -n3 "(2+2)-free posets"
S A079144 1,1,3,19,207,3451,81663,2602699,107477247,5581680571,356046745023,
N A079144 Number of labeled interval orders on n elements: (2+2)-free posets.
S A022493 1,1,2,5,15,53,217,1014,5335,31240,201608,1422074,10886503,89903100,
N A022493 Number of linearized chord diagrams of degree n; also number of nonisomorphic interval orders on n unlabeled points.
S A006531 1,1,3,19,183,2371,38703,763099,17648823,468603091,14050842303,
N A006531 Semiorders on n elements.
```

Look at those 3 results in firefox:

```
$ firefox `sloane --url -n3 "(2+2)-free posets"`
```

## Keys

These are the keys used by OEIS.

```
I ID number
S 1st line of unsigned sequence
T 2nd line of unsigned sequence
U 3rd line of unsigned sequence
V 1st line of signed sequence
W 2nd line of signed sequence
X 3rd line of signed sequence
N Name
C Comments
D References
H Links
F Formula
e Examples
p Maple program
t Mathematica program
o Program in other language
Y Cross-references
K Keywords
O Offset
A Author
E Extensions and errors
```

## Caveat

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