A090814 a(n)=3*(3^prime(n)-1)/denominator(B(2*prime(n))) where prime(n)=n-th prime and B(k) denotes the k-th Bernoulli number.

11, 1093, 3851, 797161, 64570081, 581130733, 1001523179, 581613367499, 308836698141973, 225141952945498681, 219716845645607147, 164128483697268538813, 13294407179478751643893, 90575914334953364003723

Offset

3,1

Comments

Appears to be an integer for n from 3 up to 250.

Links

Table of n, a(n) for n=3..16.

Mathematica

pB[n_]:=Module[{p=Prime[n]}, 3 (3^p-1)/Denominator[BernoulliB[2p]]]; Array[ pB, 20, 3] (* Harvey P. Dale, Apr 20 2019 *)

Prog

(PARI) a(n)=3*(3^prime(n)-1)/denominator(bernfrac(2*prime(n)))

Crossrefs

Sequence in context: A227323 A126197 A355546 * A347846 A319424 A348269

Adjacent sequences: A090811 A090812 A090813 * A090815 A090816 A090817

Keyword

nonn

Author

Benoit Cloitre, Feb 11 2004

Status

approved