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 A242016 Smallest prime factor of A135972(n), the n-th composite Mersenne number. 2
 3, 3, 3, 7, 3, 23, 3, 3, 7, 3, 3, 3, 7, 3, 47, 3, 31, 3, 7, 3, 233, 3, 3, 7, 3, 31, 3, 223, 3, 7, 3, 13367, 3, 431, 3, 7, 3, 2351, 3, 127, 3, 7, 3, 6361, 3, 23, 3, 7, 3, 179951, 3, 3, 7, 3, 31, 3, 193707721, 3, 7, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Chai Wah Wu, Table of n, a(n) for n = 1..1201 FORMULA a(n) = A020639(A135972(n)). PROG (PARI) for(n=2, 1e2, if(!ispseudoprime(2^n-1), p=factor(2^n-1)[1, 1]; print1(p, ", "))) CROSSREFS Cf. A135972, A242017. Subsequence of A056608. Sequence in context: A291767 A135087 A294505 * A084038 A326930 A095108 Adjacent sequences:  A242013 A242014 A242015 * A242017 A242018 A242019 KEYWORD nonn AUTHOR Felix FrÃ¶hlich, Aug 11 2014 STATUS approved

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Last modified September 23 03:22 EDT 2020. Contains 337291 sequences. (Running on oeis4.)