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Numerator of Bernoulli(2n)/(2n!).
4

%I #16 Sep 08 2022 08:46:11

%S 1,1,-1,1,-1,1,-691,1,-3617,43867,-174611,77683,-236364091,657931,

%T -3392780147,1723168255201,-7709321041217,151628697551,

%U -26315271553053477373,154210205991661,-261082718496449122051,1520097643918070802691

%N Numerator of Bernoulli(2n)/(2n!).

%C This sequence is different from A001067 or A046968 or A141590, at least at a(52).

%H MathOverflow, <a href="http://mathoverflow.net/questions/157115">What can be said about a function given its asymptotic expansion?</a>

%e The sequence Bernoulli(2n)/(2n!) (n >= 0) begins 1/2, 1/12, -1/120, 1/504, -1/1440, 1/3168, -691/3931200, 1/8640, -3617/41126400, ...

%t Table[Numerator[BernoulliB[2 n]/(2 n!)], {n, 0, 25}]

%o (Magma) [Numerator(Bernoulli(2*n)/(2*Factorial(n))):n in [0..30]]; // _Vincenzo Librandi_, Feb 24 2015

%o (PARI) a(n) = numerator(bernfrac(2*n)/(2*n!)); \\ _Michel Marcus_, Feb 24 2015

%o (Sage) [numerator(bernoulli(2*n)/(2*factorial(n))) for n in (0..25)] # _Bruno Berselli_, Feb 24 2015

%Y Cf. A000367, A001067, A046968, A141590, A255506 (denominator).

%K sign,frac

%O 0,7

%A _Jean-François Alcover_, Feb 24 2015