A141321 a(n) = -A141055(n)/(n+1)!.
1, 1, 10, 5, 42, 14, 60, 15, 110, 22, 5460, 910, 420, 60, 2040, 255, 11970, 1330, 23100, 2310, 15180, 1380, 163800, 13650, 3276, 252, 8120, 580, 286440, 19096, 314160, 19635, 3570, 210, 11515140, 639730, 103740, 5460
Offset: 0
Programs
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Maple
A141055 := proc(n) if n = 0 then -1; else procname(n-1)*A027760(n+2) ; end if; end proc: A141321 := proc(n) -A141055(n)/(n+1)! ; end proc: # R. J. Mathar, Jul 08 2011
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Mathematica
(* b = A141055 *) b[n_] := b[n] = b[n-1]*If[OddQ[n], 2, Denominator[BernoulliB[n+2]]]; b[0]=-1; a[n_] := -b[n]/(n+1)!; Table[a[n], {n, 0, 37}] (* Jean-François Alcover, Dec 18 2014 *)
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PARI
a(n)=if(n, my(pr=a(n-1)); fordiv(n+2, d, if(isprime(d+1), pr*=d+1)); pr, 1)/(n+1) \\ Charles R Greathouse IV, Jul 08 2011
Formula
a(2n) / a(2n+1) = n + 1.
Comments