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A090818 Nonprimes n such that 3*(3^n-1)*B(2n) is an integer, where B(k) denotes the k-th Bernoulli number. 0

%I #5 Mar 30 2012 18:39:22

%S 1,4,12,16,25,28,32,35,36,48,49,52,55,64,65,76,77,80,84,85,91,92,95,

%T 96,108,112,115,119,121,124,125,133,143,144,145,148,155,156,160,161,

%U 164,169,172,175,185,187,188,192,196,203,205,208,209,212,215,217,221,228

%N Nonprimes n such that 3*(3^n-1)*B(2n) is an integer, where B(k) denotes the k-th Bernoulli number.

%C It appears that a(n) is never == 2 (mod 4)

%o (PARI) a(n)=denominator(bernfrac(2*prime(n)))

%K nonn

%O 1,2

%A _Benoit Cloitre_, Feb 11 2004

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Last modified April 22 18:29 EDT 2024. Contains 371906 sequences. (Running on oeis4.)