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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
1, 4, 12, 16, 25, 28, 32, 35, 36, 48, 49, 52, 55, 64, 65, 76, 77, 80, 84, 85, 91, 92, 95, 96, 108, 112, 115, 119, 121, 124, 125, 133, 143, 144, 145, 148, 155, 156, 160, 161, 164, 169, 172, 175, 185, 187, 188, 192, 196, 203, 205, 208, 209, 212, 215, 217, 221, 228 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
It appears that a(n) is never == 2 (mod 4)
LINKS
PROG
(PARI) a(n)=denominator(bernfrac(2*prime(n)))
CROSSREFS
Sequence in context: A186303 A073687 A187084 * A075191 A320922 A028594
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 11 2004
STATUS
approved

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Last modified February 26 20:11 EST 2024. Contains 370352 sequences. (Running on oeis4.)