A097521 Difference between F(n) = 2^(2^n)+1 and nextprime(F(n)) where F(n) is the n-th Fermat Number.

2, 2, 2, 6, 2, 14, 12, 50, 296, 74, 642, 980, 1760, 896, 2774, 118112, 44060, 5850

Offset: 0

Author

Cino Hilliard, Aug 27 2004

Keywords

• nonn
• more

Comments

In the Name, nextprime means A151800, not A007918. - Jeppe Stig Nielsen, Nov 18 2019

a(n) = A129786(n)-1 except in the rare case that F(n) is a prime. - Jeppe Stig Nielsen, Nov 18 2019

Examples

			F(5) = 4294967297. Nextprime(F(5)) = 4294967311.
4294967311 - 4294967297 = 14 the 6th entry in the table.
		

Crossrefs

Cf. A000215, A013632, A151800, A129786.

Programs

PARI

for(n=0,+oo,print1(nextprime(2^(2^n)+2)-(2^(2^n)+1),", ")) \\ Jeppe Stig Nielsen, Nov 18 2019

Formula

a(n) = A013632(A000215(n)). - Michel Marcus, Nov 18 2019

Extensions

More terms with the help of A129786 from Jeppe Stig Nielsen, Nov 18 2019