A159270 Number of positive integers m<=n such that 2^m+3^n or 2^n+3^m is prime.

0, 1, 2, 2, 3, 3, 3, 4, 5, 3, 5, 3, 6, 6, 4, 4, 7, 6, 8, 4, 4, 4, 4, 6, 7, 2, 4, 5, 6, 6, 8, 6, 10, 3, 3, 5, 6, 4, 9, 6, 9, 7, 5, 5, 9, 6, 8, 7, 7, 10, 4, 5, 8, 9, 1, 8, 6, 6, 7, 7, 10, 5, 5, 4, 10, 8, 7, 8, 8, 2, 3, 8, 8, 8, 5, 6, 7, 5, 10, 6, 7, 7, 8, 10, 10, 9, 10, 5, 7, 5, 5, 6, 9, 6, 5, 5, 12, 3, 7, 6, 8, 9

Offset: 0

Author

M. F. Hasler, Apr 09 2009

Keywords

• nonn

Comments

Zeros occur at n = 0 and for n in A159625.

For the values in A159625 both A159266(x) and A123359(x) are greater than x. - Michel Marcus, Apr 07 2014

Links

• Michel Marcus, Table of n, a(n) for n = 0..2000
• David Broadhurst, 2^m+3^n and 2^n+3^m, Prime numbers and primality testing Group, Apr 11 2009. [Broken link]
• Maximilian Hasler, Mike Oakes, Mark Underwood, David Broadhurst and others, Primes of the form (x+1)^p-x^p, digest of 22 messages in primenumbers Yahoo group, Apr 5 - May 7, 2009. [Cached copy]
• Mark Underwood, Re: primes of the form (x+1)^p-x^p, Prime numbers and primality testing Group, Apr 07 2009. [Broken link]

Crossrefs

Cf. A159266, A123359, A159625.

Programs

PARI

A159270(n)=sum(m=1,n, ispseudoprime(2^n+3^m) || ispseudoprime(3^n+2^m))