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A059764 Initial (unsafe) primes of Cunningham chains of first type with length exactly 5. Primes in A059453 which survive as primes just four "2p+1 iterations", forming chains of exactly 5 terms. +0
12
2, 53639, 53849, 61409, 66749, 143609, 167729, 186149, 206369, 268049, 296099, 340919, 422069, 446609, 539009, 594449, 607319, 658349, 671249, 725009, 775949, 812849, 819509, 926669, 1008209, 1092089, 1132949, 1271849 (list; graph; listen)
OFFSET

1,1

LINKS

Chris Caldwell's Prime Glossary, Cunningham chains.

FORMULA

{(p-1)/2, p, 2p+1, 4p+3, 8p+7, 16p+15, 32p+31} = {nonprime, prime, prime, prime, prime, prime, composite}

EXAMPLE

2 is here because (2-1)/2=1/2 and 32*2+31=95 are not primes, while 2,5,11,23,47 gives a first-kind-Cu5-chain of 5 primes which cannot be continued.

53639 is here because through <2p+1>, 53639 -> 107279 -> 214559 -> 429119 -> 858239 and the chain ends here (with this operator).

CROSSREFS

Cf. A023272, A023302, A023330, A005384, A005385, A059452-A059455, A007700, A059759, A059760, A059761, A059762, A059763, A059764, A059765, A038397, A104349, A091314, A069362, A016093, A014937, A057326.

Sequence in context: A157959 A094213 A153924 this_sequence A052427 A051833 A060895

Adjacent sequences: A059761 A059762 A059763 this_sequence A059765 A059766 A059767

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Feb 20 2001

EXTENSIONS

Definition corrected by Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Aug 31 2005

Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Apr 01 2006

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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