A006956 Denominator of (2n+1)(2n+2) B_{2n}, where B_n are the Bernoulli numbers. Also denominators of the asymptotic expansion of the polygamma function psi'''(z). (Formerly M2211)

1, 1, 1, 1, 3, 1, 1, 15, 1, 5, 21, 5, 1, 21, 1, 1, 231, 5, 1, 1365, 1, 55, 21, 1, 1, 663, 11, 5, 57, 5, 1, 15015, 1, 17, 483, 1, 11, 25935, 1, 5, 21, 935, 1, 7917, 1, 23, 19437, 5, 1, 3315, 1, 55, 21, 1, 1, 191919, 253, 2465, 21, 5, 1, 1734915, 1, 1, 17157, 17, 1

Offset

3,5

References

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 260, (6.4.14).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Vincenzo Librandi, Table of n, a(n) for n = 3..1000

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 260, (6.4.14).

Mathematica

Join[{1, 1}, Table[Denominator[(4 n^2 + 6 n + 2) BernoulliB[2 n]], {n, 1, 70}]] (* Vincenzo Librandi, Aug 02 2013 *)

Crossrefs

Numerators are in A076549. Cf. A006955/A002427.

Sequence in context: A153090 A203002 A073483 * A072285 A144269 A144270

Adjacent sequences: A006953 A006954 A006955 * A006957 A006958 A006959

Keyword

nonn,frac

Author

Simon Plouffe

Extensions

More terms from Ralf Stephan, Oct 19 2002

Status

approved