A120282 Numerator of the coefficients of k^2 term at Sum[Sum[(i-j)^(2n),{i,1,k}],{j,1,k}].

-1, 1, -5, 7, -15, 7601, -91, 3617, -745739, 3317609, -5981591, 5436374093, -213827575, 213745149261, -249859397004145, 238988952277727, -28354566442037, 26315271553053477373, -108409774812137683, 3394075340453838586663

Offset

1,3

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = numerator[Coefficient[Sum[Sum[(i-j)^(2n),{i,1,k}],{j,1,k}],k,2]]. a(n) = A027643(2n+3) - bisection of numerators of poly-Bernoulli numbers B_n^(k) with k=2.

Mathematica

Numerator[Coefficient[Table[Sum[Sum[(i-j)^(2n), {i, 1, k}], {j, 1, k}], {n, 1, 20}], k, 2]]

Crossrefs

Cf. A027643.

Sequence in context: A059613 A242503 A116048 * A132094 A082878 A106506

Adjacent sequences: A120279 A120280 A120281 * A120283 A120284 A120285

Keyword

frac,sign

Author

Alexander Adamchuk, Jul 06 2006

Status

approved