A119656 Denominator of BernoulliB(4*prime(n))/30.

1, 91, 11, 29, 23, 53, 1, 1, 47, 59, 1, 149, 83, 173, 1, 107, 1, 1, 269, 1, 293, 317, 167, 179, 389, 1, 1, 1, 1, 227, 509, 263, 1, 557, 1, 1, 1, 653, 1, 347, 359, 1, 383, 773, 1, 797, 1, 1, 1, 1, 467, 479, 1, 503, 1, 1, 1, 1, 1109, 563, 1, 587, 1229, 1, 1, 1, 1, 1, 1, 1, 1, 719

Offset

1,2

Comments

The only composite in this sequence is a(2) = 91 = 7*13. All other a(n) are equal to 1 (for n = 1,7,8,11,15,17,18,20,26,27,28,29,33,35,36,37,39,...) or primes from A090865. Each prime from A090865 (excluding 7 and 13) appears only once in {a(n)}. The primes in {a(n)} also appear to form a subset of A103203.

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

a(n) = denominator(BernoulliB(4*prime(n)))/30.

Mathematica

Table[Denominator[BernoulliB[4Prime[n]]]/30, {n, 1, 80}]

Prog

(PARI) {a(n) = denominator(bernfrac(4*prime(n)))/30};
vector(80, n, a(n)) \\ G. C. Greubel and Michel Marcus, Feb 10 2019
(Magma) [Denominator(Bernoulli(4*NthPrime(n)))/30: n in [1..80]]; // G. C. Greubel, Feb 10 2019
(Sage)  [denominator(bernoulli(4*nth_prime(n)))/30 for n in (1..80)] # G. C. Greubel, Feb 10 2019

Crossrefs

Cf. A090865, A103203, A005385, A002445.

Sequence in context: A283896 A284439 A364664 * A368238 A339141 A180006

Adjacent sequences: A119653 A119654 A119655 * A119657 A119658 A119659

Keyword

nonn

Author

Alexander Adamchuk, Jul 28 2006

Status

approved