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 A073409 Largest prime factor of the denominator of the Bernoulli number B(2*n) (A002445). 1
 3, 5, 7, 5, 11, 13, 3, 17, 19, 11, 23, 13, 3, 29, 31, 17, 3, 37, 3, 41, 43, 23, 47, 17, 11, 53, 19, 29, 59, 61, 3, 17, 67, 5, 71, 73, 3, 5, 79, 41, 83, 43, 3, 89, 31, 47, 3, 97, 3, 101, 103, 53, 107, 109, 23, 113, 7, 59, 3, 61, 3, 5, 127, 17, 131, 67, 3, 137, 139, 71, 3, 73, 3, 149 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Least k such that k!*B(2n) is an integer where B(2n) denotes the 2n-th Bernoulli number. a((p-1)/2) = p, where p is odd prime. All odd primes appear in this sequence. The very first appearance of odd prime p is a((p-1)/2). - Alexander Adamchuk, Jul 31 2006 LINKS MATHEMATICA Table[FactorInteger[Denominator[BernoulliB[2n]]][[ -1, 1]], {n, 100}] PROG (PARI) a(n)= {     my(bd=1);     forprime (p=2, 2*n+1, if( (2*n)%(p-1)==0, bd=p ) );     return(bd); } /* Joerg Arndt, May 06 2012 */ CROSSREFS Cf. A005097. Sequence in context: A141574 A141261 A077129 * A260234 A151548 A256258 Adjacent sequences:  A073406 A073407 A073408 * A073410 A073411 A073412 KEYWORD easy,nonn AUTHOR Benoit Cloitre, Aug 23 2002 STATUS approved

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Last modified October 23 17:32 EDT 2019. Contains 328373 sequences. (Running on oeis4.)