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Denominators of Bernoulli numbers interleaved with even numbers.
7

%I #23 Sep 08 2022 08:45:47

%S 1,2,6,4,30,6,42,8,30,10,66,12,2730,14,6,16,510,18,798,20,330,22,138,

%T 24,2730,26,6,28,870,30,14322,32,510,34,6,36,1919190,38,6,40,13530,42,

%U 1806,44,690,46,282,48,46410,50,66,52,1590,54,798,56,870,58,354,60,56786730

%N Denominators of Bernoulli numbers interleaved with even numbers.

%H G. C. Greubel, <a href="/A164020/b164020.txt">Table of n, a(n) for n = 0..1000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/BernoulliNumber.html">Bernoulli Number</a>

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

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

%F a(n) divides A057643(n). _Franklin T. Adams-Watters_, Aug 03 2012

%t a[n_]:=If[OddQ[n], n+1, BernoulliB[n] // Denominator]; Table[a[n], {n, 0, 60}](* _Jean-François Alcover_, Dec 29 2012 *)

%t With[{nn=60},Riffle[Denominator[BernoulliB[Range[0,nn,2]]],Range[2,nn,2]]] (* _Harvey P. Dale_, Jul 18 2015 *)

%o (Magma) [IsEven(n) select Denominator(Bernoulli(n)) else n+1: n in [0..100]]; // _Vincenzo Librandi_, Sep 08 2017

%Y Cf. A027642, A141056, A160014.

%K nonn

%O 0,2

%A _Paul Curtz_, Aug 08 2009

%E Extended by _R. J. Mathar_, Sep 23 2009