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A119563 Define F(n) = 2^(2^n)+1 = n-th Fermat number, M(n) = 2^n-1 = the n-th Mersenne number. Then a(n) = F(n)+M(n)-1 = 2^(2^n) + 2^n - 1. 7
2, 5, 19, 263, 65551, 4294967327, 18446744073709551679, 340282366920938463463374607431768211583, 115792089237316195423570985008687907853269984665640564039457584007913129640191 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The first 5 entries are primes. Are there infinitely many primes in this sequence?

LINKS

Table of n, a(n) for n=0..8.

FORMULA

a(n) = A119561(n)-2=A000215(n)+A000225(n)-1. - R. J. Mathar, Apr 22 2007

EXAMPLE

F(2) = 2^(2^2)+1 = 17, M(2) = 2^2-1 = 3, F(2)+ M(2) - 1 = 19

PROG

(PARI) fm3(n) = for(x=0, n, y=2^(2^x)+2^x-1; print1(y", "))

CROSSREFS

Sequence in context: A218386 A055813 A119550 * A270398 A269997 A270547

Adjacent sequences:  A119560 A119561 A119562 * A119564 A119565 A119566

KEYWORD

nonn

AUTHOR

Cino Hilliard, May 31 2006

EXTENSIONS

Edited by N. J. A. Sloane, Jun 03 2006

STATUS

approved

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Last modified July 12 22:46 EDT 2020. Contains 335669 sequences. (Running on oeis4.)