A087858 - OEIS

This site is supported by donations to The OEIS Foundation.

A087858

Lesser of twin primes p such that 2^p-1 is prime.

3, 5, 17, 107, 521 (list; graph; refs; listen; history; internal format)

	OFFSET	`2,1`
	COMMENTS	`Are there any further terms?`
	PROG	`(PARI) twopm1(n) = { sr=0; forprime(x=2, n, y=2^x-1; if(isprime(x+2), y2=2^(x+2)-1, y2=0); if(isprime(y) && isprime(x+2), print1(x", "); sr+=1.0/y; sr+=1.0/y2; ) ); }`
	CROSSREFS	`Sequence in context: A114161 A174722 A176131 * A191222 A084723 A107312` `Adjacent sequences: A087855 A087856 A087857 * A087859 A087860 A087861`
	KEYWORD	`easy,nonn`
	AUTHOR	`Cino Hilliard (hillcino368(AT)gmail.com), Oct 25 2003`

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

Last modified February 15 05:29 EST 2012. Contains 205694 sequences.