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 A157779 Numerator of Bernoulli(n, 1/2). 10
 1, 0, -1, 0, 7, 0, -31, 0, 127, 0, -2555, 0, 1414477, 0, -57337, 0, 118518239, 0, -5749691557, 0, 91546277357, 0, -1792042792463, 0, 1982765468311237, 0, -286994504449393, 0, 3187598676787461083, 0, -4625594554880206790555, 0, 16555640865486520478399, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Included for completeness, normally alternating zeros like this are omitted. A001896 is the official version of this sequence. The sequence {a(n)/A141459(n)} gives the generalized Bernoulli numbers B[2,1] obtained from the generalized Stirling2 triangle S3[2,1] = A154537. See the formula section. - Wolfdieter Lang, Apr 27 2017 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..250 Wolfdieter Lang, On Sums of Powers of Arithmetic Progressions, and Generalized Stirling, Eulerian and Bernoulli Numbers, arXiv:math/1707.04451 [math.NT], July 2017. FORMULA Let P(x) = Sum_{n>=0} x^(2*n+1)/(2*n+1)!; then a(n) = numerator( n! [x^n] x/P(x) ). - Peter Luschny, Jul 05 2016 a(n) = numerator(r(n)) with the rationals r(n) = Sum_{k=0..n} ((-1)^k / (k+1))*A154537(n, k)*k! = Sum_{k=0..n} ((-1)^k/(k+1))*A145901(n, k). The denominators are in A141459. r(n) = B[2,1](n) = 2^n*B(n, 1/2) with the Bernoulli polynomials A196838/A196839 or A053382/A053383. - Wolfdieter Lang, Apr 27 2017 a(n) = numerator(-(1-2^(1-n))*Bernoulli(n)). - Fabián Pereyra, Dec 31 2022 MATHEMATICA Numerator[BernoulliB[Range[0, 40], 1/2]] (* Harvey P. Dale, May 04 2013 *) PROG (Sage) def A157779_list(size): f = x / sum(x^(n*2+1)/factorial(n*2+1) for n in (0..2*size)) t = taylor(f, x, 0, size) return [(factorial(n)*s).numerator() for n, s in enumerate(t.list())] print(A157779_list(33)) # Peter Luschny, Jul 05 2016 (PARI) a(n) = numerator(subst(bernpol(n, x), x, 1/2)); \\ Altug Alkan, Jul 05 2016 CROSSREFS For denominators see A157780 and A141459. Sequence in context: A282677 A280143 A280144 * A222322 A228762 A352078 Adjacent sequences: A157776 A157777 A157778 * A157780 A157781 A157782 KEYWORD sign,frac AUTHOR N. J. A. Sloane, Nov 08 2009 STATUS approved

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Last modified September 24 16:50 EDT 2023. Contains 365579 sequences. (Running on oeis4.)