cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A262235 Denominators of a series leading to Euler's constant gamma.

Original entry on oeis.org

4, 72, 32, 14400, 1728, 2540160, 138240, 261273600, 896000, 10538035200, 209018880, 407994402816000, 5633058816000, 941525544960000, 4723310592, 8707228239790080000, 6162712657920000, 17473102222724628480000, 107559878256230400000, 14162409169997856768000000
Offset: 1

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Comments

Gamma = 1 - 1/4 - 5/72 - 1/32 - 251/14400 - 19/1728 - 19087/2540160 - ..., see the references below.

Examples

			Denominators of 1/4, 5/72, 1/32, 251/14400, 19/1728, 19087/2540160, ...
		

Crossrefs

Programs

  • Maple
    a := proc(n) local r; r := proc(n) option remember; if n=0 then 1 else
    1 - add(r(k)/(n-k+1), k=0..n-1) fi end: denom(r(n)/(n*(n+1))) end:
    seq(a(n), n=1..20); # Peter Luschny, Apr 19 2018
  • Mathematica
    g[n_] := Sum[Abs[StirlingS1[n, l]]/(l + 1), {l, 1, n}]/(n*(n + 1)!); a[n_] := Denominator[g[n]]; Table[a[n], {n, 1, 20}]

Formula

a(n) = C2(n)/(n*(n + 1)!), where C2(n) are Cauchy numbers of the second kind (see A002657 and A002790).