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A059500 Primes p such that both q=(p-1)/2 and 2p+1=4q+3 are composite numbers. Intersection of A059456 and A053176. +0
4
13, 17, 19, 31, 37, 43, 61, 67, 71, 73, 79, 97, 101, 103, 109, 127, 137, 139, 149, 151, 157, 163, 181, 193, 197, 199, 211, 223, 229, 241, 257, 269, 271, 277, 283, 307, 311, 313, 317, 331, 337, 349, 353, 367, 373, 379, 389, 397, 401, 409, 421, 433, 439, 449 (list; graph; listen)
OFFSET

1,1

COMMENT

Primes which are neither safe nor of Sophie Germain type.

Primes not in Cunningham chains of the first kind. - Alonso Delarte (alonso.delarte(AT)gmail.com), Jun 30 2005

LINKS

C. K. Caldwell, Cunningham Chains

EXAMPLE

Prime p=17 is here because both 35 and 8 are composite numbers. Such primes fall "out of" any Cunningham chain of first kind (or generate Cunningham chains of 0-length).

MATHEMATICA

Complement[Prime[Range[100]], Select[Prime[Range[100]], PrimeQ[2# + 1] &], Select[Prime[Range[100]], PrimeQ[(# - 1)/2] &]] (Delarte)

CROSSREFS

A005384, A005385, A053176, A059452-A059456, A007700, A005602, A023272, A023302, A023330.

Adjacent sequences: A059497 A059498 A059499 this_sequence A059501 A059502 A059503

Sequence in context: A054476 A099184 A098095 this_sequence A104213 A105896 A112741

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Feb 05 2001

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Last modified October 13 09:05 EDT 2008. Contains 145008 sequences.


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