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A111877 Sequence related to f(n) = 1/1 + 1/3 + ... + 1/(2n+1). 1
1, 5, 35, 105, 1155, 15015, 15015, 255255, 4849845, 4849845, 111546435, 557732175, 1673196525, 48522699225, 1504203675975, 1504203675975, 1504203675975, 55655536011075, 55655536011075, 2281876976454075, 98120709987525225 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

FORMULA

a(n)=denominator(digamma(n+5/2)/2+log(2)+euler_gamma/2)/3; a(n)=denominator(f(n+1)/3).

MATHEMATICA

f[x_] := 2 x + 1; a[1] = f[1]; a[n_] := LCM[f[n], a[n - 1]]; Array[a, 21]/3 (* Robert G. Wilson v, Jan 04 2013 *)

CROSSREFS

Cf. A025547.

Sequence in context: A090294 A162540 A161199 * A179337 A053126 A096743

Adjacent sequences:  A111874 A111875 A111876 * A111878 A111879 A111880

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Aug 19 2005

STATUS

approved

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Last modified June 12 21:39 EDT 2021. Contains 344968 sequences. (Running on oeis4.)