A281332 Greatest prime factor of |A001067(n)|, or 1 if |A001067(n)| = 1.
1, 1, 1, 1, 1, 691, 1, 3617, 43867, 617, 593, 2294797, 657931, 362903, 1001259881, 305065927, 151628697551, 26315271553053477373, 154210205991661, 1897170067619, 1520097643918070802691, 1798482437, 67568238839737, 153289748932447906241, 47464429777438199
Offset: 1
Keywords
Examples
|A001067(10)| = 174611 = 283*617. So a(10) = 617. |A001067(16)| = 7709321041217 = 37*683*305065927. So a(16) = 305065927.
Programs
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Mathematica
Table[FactorInteger[Abs@ Numerator[BernoulliB[2 n]/(2 n)]][[-1, 1]], {n, 25}] (* Michael De Vlieger, Jan 21 2017 *) -
PARI
a(n) = if(abs(numerator(bernfrac(2*n) / (2*n))) == 1, 1, vecmax(factor(abs(numerator(bernfrac(2*n) / (2*n))))[,1])); for(n=1, 25, print1(a(n), ", ")) \\ Indranil Ghosh, Mar 11 2017
Extensions
a(20)-a(25) from Michael De Vlieger, Jan 21 2017