A229023 Numerators of the main diagonal of A225825 difference table, a sequence linked to Bernoulli, Genocchi and Clausen numbers.

1, -2, 16, -424, 2944, -70240, 70873856, -212648576, 98650550272, -90228445612544, 19078660567134208, -2034677178643867648, 123160010212358914048, -19182197131374977024, 228111332170536254898176, -51166426240975948419354886144

Offset

0,2

Comments

a(n) is divisible by 2^n and congruent to 1, 2, 4, 5, 7 or 8 mod 9.

Links

Table of n, a(n) for n=0..15.

Example

1, -2/3, 16/15, -424/105, 2944/105, -70240/231, 70873856/15015, ...

Mathematica

nmax = 30; Clausen[n_] := Times @@ Select[Divisors[n] + 1, PrimeQ]; t = Join[{1}, Table[Numerator[BernoulliB[n, 1/2] - (n + 1)*EulerE[n, 0]]/Clausen[n], {n, 1, nmax}]]; dt = Table[Differences[t, n], {n, 0, nmax}]; Diagonal[dt] // Numerator

Crossrefs

Cf. A181131 (denominators), A225825, A110501 (Genocchi numbers), A141056 (Clausen numbers), A212196 (Bernoulli medians), A005439 (Genocchi medians).

Sequence in context: A343428 A282309 A009397 * A009700 A358784 A012030

Adjacent sequences: A229020 A229021 A229022 * A229024 A229025 A229026

Keyword

frac,sign,easy

Author

Jean-François Alcover and Paul Curtz, Sep 11 2013

Status

approved