id:A159266 - OEIS Search Results

Search: id:A159266

Displaying 1-1 of 1 results found.

page 1

Least positive integer m such that 2^n+3^m is prime.

+0
2

1, 1, 1, 1, 2, 1, 1, 3, 2, 2, 4, 1, 3, 3, 1, 1, 8, 1, 4, 8, 8, 6, 2, 7, 27, 6, 13, 1, 10, 1, 6, 4, 8, 18, 9, 19, 2, 15, 29, 3, 3, 17, 10, 3, 11, 6, 2, 5, 20, 34, 4, 12, 10, 26, 1, 4, 2, 9, 29, 29, 10, 34, 13, 4, 8, 2, 1, 8, 10, 26, 50, 19, 12, 10, 8, 13, 27, 17, 9, 33, 4, 2, 17, 1, 7, 3, 5, 61, 26 (list; graph; listen)

	OFFSET	`1,5`
	COMMENT	`In contrast to A123340 which allows m=0, a(0) does not exist for this sequence.`
	LINKS	`M. F. Hasler, Primes of the form (x+1)^p-x^p, Apr 7, 2009.`
	FORMULA	`a(n) = min { m>0 \| 2^n+3^m is prime } = A123340(n) whenever the latter is > 1.`
	EXAMPLE	`a(1)=1 is the least m>0 such that 2^1+3^m (=5) is prime.` `a(2)=1 is the least m>0 such that 2^2+3^m (=7) is prime.` `a(5)=2 is the least m>0 such that 2^5+3^m (=41) is prime.`
	PROGRAM	`(PARI) A159266(n, m=0)=until( is/pseudo/prime(2^n+3^m++), ); m) /* 2nd optional arg allows us to resume search after a given m and thus (when set to previous result) the list of all m yielding primes */`
	CROSSREFS	`Cf. A123340 (allows for m=0), A123359 (roles of 2 and 3 exchanged).` `Sequence in context: A060118 A029308 A029259 this_sequence A161065 A161104 A110248` `Adjacent sequences: A159263 A159264 A159265 this_sequence A159267 A159268 A159269`
	KEYWORD	`nonn`
	AUTHOR	`M. F. Hasler (MHasler(AT)univ-ag.fr), Apr 07 2009`

page 1

Search completed in 0.002 seconds

Last modified November 24 19:38 EST 2009. Contains 167438 sequences.

AT&T Labs Research