A242017 -id:A242017 - cp's OEIS frontend

A372867 Distinct terms in A242017, listed in the order of their appearance.

3, 5, 17, 97, 641, 257, 193, 274177, 65537, 449, 59649589127497217, 769, 1238926361552897, 5441, 5953, 2424833, 7873, 2753, 3329, 10753, 45592577, 18433, 4673, 15937, 444929, 11777, 12161, 21698561, 6977

Offset: 1

Jean-Marc Rebert, May 15 2024

Conjecture: every term except 3 belongs to A366609. - Bill McEachen, Jun 12 2024

Cf. A023394, A070592, A093179, A242017.

A242016 Smallest prime factor of A135972(n), the n-th composite Mersenne number.

Original entry on oeis.org

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

Offset: 1

Felix Fröhlich, Aug 11 2014

nonn

Chai Wah Wu, Table of n, a(n) for n = 1..1201

Cf. A135972, A242017. Subsequence of A056608.

for(n=2, 1e2, if(!ispseudoprime(2^n-1), p=factor(2^n-1)[1, 1]; print1(p, ", ")))

a(n) = A020639(A135972(n)).

cp's OEIS Frontend

A372867 Distinct terms in A242017, listed in the order of their appearance.

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A242016 Smallest prime factor of A135972(n), the n-th composite Mersenne number.

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