A047681 a(n) = 3^(2*n)*(3^(2*n)-1)*Bernoulli(2*n)/(2*n).

6, -54, 2106, -179334, 26414586, -5957217414, 1906398972666, -821369346492294, 458382160232420346, -321645776191296739974, 277173760840187306341626, -287758284647458145849816454, 354245505704926834826124160506, -510230879113388713374134585497734

Offset: 1

Author

N. J. A. Sloane

Keywords

• sign

References

• J. W. Milnor and J. D. Stasheff, Characteristic Classes, Princeton, 1974, p. 283.

Links

• Index entries for sequences related to Bernoulli numbers.

Programs

Magma

[3^(2*n)*(3^(2*n) - 1)*Bernoulli(2*n) / (2*n):n in [1..30]]; // Vincenzo Librandi, Apr 08 2020

Mathematica

Table[3^(2 n) (3^(2 n) - 1) BernoulliB[2 n] / (2 n), {n, 25}] (* Vincenzo Librandi, Apr 08 2020 *)

PARI

a(n) = 3^(2*n)*(3^(2*n)-1)*bernfrac(2*n)/(2*n); \\ Michel Marcus, Mar 07 2020