A090947 Largest prime factor of numerator of Bernoulli(2n) (or 1 if the numerator is 1).

1, 1, 1, 1, 1, 5, 691, 7, 3617, 43867, 617, 593, 2294797, 657931, 362903, 1001259881, 305065927, 151628697551, 26315271553053477373, 154210205991661, 1897170067619, 1520097643918070802691, 1798482437, 67568238839737, 153289748932447906241, 47464429777438199, 4534045619429, 1120412849144121779, 19088082706840550550313, 37349583369104129, 109317926249509865753025015237911, 28765594733083851481, 87057315354522179184989699791727, 159562251828620181390358590156239282938769, 5525473366510930028227481

Offset

0,6

Links

Amiram Eldar, Table of n, a(n) for n = 0..103

Formula

a(n) = A006530(abs(A000367(n))). - Amiram Eldar, Feb 09 2020

Mathematica

PrimeFactors[ n_] := Flatten[ Table[ #[[1]], {1} ] & /@ FactorInteger[ n ]]; A090947[n_] := PrimeFactors[ Numerator[ BernoulliB[2n]]][[ -1]]; Table[ A090947[n], {n, 5, 24}] (* Robert G. Wilson v, Feb 28 2004 *)

Crossrefs

Cf. A000367, A006530, A079294.

Sequence in context: A332300 A242193 A326727 * A176840 A000367 A176546

Adjacent sequences: A090944 A090945 A090946 * A090948 A090949 A090950

Keyword

nonn

Author

N. J. A. Sloane, Feb 28 2004

Extensions

More terms from Robert G. Wilson v and Hans Havermann, Feb 28 2004

Status

approved