A123536 a(0) = 1; for n > 0, a(n) = (-1)^(n+1)*B(2n)*Product_{prime p<=2n+1} p where B(2n) denotes the (2n)-th Bernoulli number.

1, 1, 1, 5, 7, 175, 7601, 35035, 3620617, 533203385, 5132341123, 1381418533495, 19315437152429, 318022715945935, 176611180730425441, 120653354922346558325, 3031735699207849905271, 86163723379372590236285, 101750602671765022556964427, 3623786261867543729253761465

Offset

0,4

Links

Table of n, a(n) for n=0..19.

Maple

seq(abs(bernoulli(n)*A034386(n+1)), n=0..38, 2); # Peter Luschny, Oct 02 2017

Mathematica

P[n_] := Times @@ Array[Prime, PrimePi[n]];
a[n_] := Abs[BernoulliB[2n]] P[2n+1];
Table[a[n], {n, 0, 19}] (* Jean-François Alcover, Jun 13 2019 *)

Prog

(PARI) a(n) = if(n==0, 1, (-1)^(n+1)*bernfrac(2*n)*prod(p=1, 2*n+1, if(isprime(p), p, 1)))

Crossrefs

Cf. A002445, A034386.

Sequence in context: A083842 A164372 A318088 * A057177 A297535 A211769

Adjacent sequences: A123533 A123534 A123535 * A123537 A123538 A123539

Keyword

nonn

Author

Benoit Cloitre, Nov 11 2006

Status

approved