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A087693
Lesser twin prime p such that 2^p-1 is composite.
0
11, 29, 41, 59, 71, 101, 137, 149, 179, 191, 197, 227, 239, 269, 281, 311, 347, 419, 431, 461, 569, 599, 617, 641, 659, 809, 821, 827, 857, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1229, 1277, 1289, 1301, 1319, 1427, 1451, 1481, 1487, 1607, 1619, 1667, 1697
OFFSET
0,1
COMMENTS
Look at all twin primes (p1, p2); if 2^p1 - 1 is composite print p2.
PROG
(PARI) twopm1(n) = { forprime(x=2, n, y=2^x-1; if(!isprime(y) && isprime(x+2), print1(x", ") ) ) }
CROSSREFS
Sequence in context: A353043 A350420 A240678 * A106017 A343418 A106065
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Oct 25 2003
EXTENSIONS
More terms from Ray Chandler, Nov 07 2003
STATUS
approved