A164020 Denominators of Bernoulli numbers interleaved with even numbers.

1, 2, 6, 4, 30, 6, 42, 8, 30, 10, 66, 12, 2730, 14, 6, 16, 510, 18, 798, 20, 330, 22, 138, 24, 2730, 26, 6, 28, 870, 30, 14322, 32, 510, 34, 6, 36, 1919190, 38, 6, 40, 13530, 42, 1806, 44, 690, 46, 282, 48, 46410, 50, 66, 52, 1590, 54, 798, 56, 870, 58, 354, 60, 56786730

Offset: 0

Author

Paul Curtz, Aug 08 2009

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000
• Eric Weisstein's World of Mathematics, Bernoulli Number

Crossrefs

Cf. A027642, A141056, A160014.

Programs

Magma

[IsEven(n) select Denominator(Bernoulli(n)) else n+1: n in [0..100]]; // Vincenzo Librandi, Sep 08 2017

Mathematica

a[n_]:=If[OddQ[n], n+1, BernoulliB[n] // Denominator]; Table[a[n], {n, 0, 60}](* Jean-François Alcover, Dec 29 2012 *)
With[{nn=60},Riffle[Denominator[BernoulliB[Range[0,nn,2]]],Range[2,nn,2]]] (* Harvey P. Dale, Jul 18 2015 *)

Formula

a(2*n) = A002445(n).

a(2*n+1) = 2*(n+1).

a(n) divides A057643(n). Franklin T. Adams-Watters, Aug 03 2012

Extensions

Extended by R. J. Mathar, Sep 23 2009