login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A156658 Primes p such that also 2*p+1 or (p-1)/2 is prime. 2
2, 3, 5, 7, 11, 23, 29, 41, 47, 53, 59, 83, 89, 107, 113, 131, 167, 173, 179, 191, 227, 233, 239, 251, 263, 281, 293, 347, 359, 383, 419, 431, 443, 467, 479, 491, 503, 509, 563, 587, 593, 641, 653, 659, 683, 719, 743, 761, 809, 839, 863, 887, 911, 953, 983, 1013 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Union of A005384 and A005385;

A156660(a(n)) + A156659(a(n)) > 0;

primes occuring in Cunningham chains of the first kind.

A156876 gives the number of these numbers <= n. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 18 2009]

LINKS

Wikipedia, Sophie Germain prime

Wikipedia, Safe prime

Wikipedia, Cunningham chain

CROSSREFS

A059500.

Sequence in context: A089392 A089695 A070027 * A118723 A118721 A094318

Adjacent sequences:  A156655 A156656 A156657 * A156659 A156660 A156661

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 13 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 16 11:42 EST 2012. Contains 205907 sequences.