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A140219 Denominator of the coefficient [x^1] of the Bernoulli twin number polynomial C(n,x). 2
1, 1, 2, 2, 6, 6, 6, 6, 10, 10, 6, 6, 210, 210, 2, 2, 30, 30, 42, 42, 110, 110, 6, 6, 546, 546, 2, 2, 30, 30, 462, 462, 170, 170, 6, 6, 51870, 51870, 2, 2, 330, 330, 42, 42, 46, 46, 6, 6, 6630, 6630, 22, 22, 30, 30, 798, 798, 290 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See A140351 for the main part of the documentation.

LINKS

Table of n, a(n) for n=0..56.

FORMULA

a(n) = denominator(Sum_{i=0..n} binomial(n,i)*(i+1)*bern(i)). - Vladimir Kruchinin, Oct 05 2016

MAPLE

C := proc(n, x) if n = 0 then 1; else add(binomial(n-1, j-1)* bernoulli(j, x), j=1..n) ; expand(%) ; end if ; end proc:

A140219 := proc(n) coeff(C(n, x), x, 1) ; denom(%) ; end proc:

seq(A140219(n), n=1..80) ; # R. J. Mathar, Sep 22 2011

MATHEMATICA

Table[Sum[Binomial[n, k]*(k+1)*BernoulliB[k], {k, 0, n}], {n, 0, 60}] // Denominator (* Vaclav Kotesovec, Oct 05 2016 *)

PROG

(Maxima) makelist(denom(sum((binomial(n, i)*(i+1)*bern(i)), i, 0, n)), n, 0, 20); /* Vladimir Kruchinin, Oct 05 2016 */

(PARI) a(n) = denominator(sum(i=0, n, binomial(n, i)*(i+1)*bernfrac(i))); \\ Michel Marcus, Oct 05 2016

CROSSREFS

Cf. A140351 (numerators), A048594.

Sequence in context: A324032 A196872 A319865 * A259225 A300951 A077081

Adjacent sequences:  A140216 A140217 A140218 * A140220 A140221 A140222

KEYWORD

nonn,frac

AUTHOR

Paul Curtz, Jun 23 2008

STATUS

approved

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Last modified June 17 12:26 EDT 2021. Contains 345080 sequences. (Running on oeis4.)