

A116896


Numbers k such that k! + k!! + 1 is prime, where k!! denotes double factorial (A001147).


1




OFFSET

1,3


COMMENTS

1976! + 1976!! + 1 is a 5657digit prime. Next term is greater than 4000.


LINKS

Table of n, a(n) for n=1..8.
Joe McLean, Interesting Sources of Probable Primes


EXAMPLE

6! + 6!! + 1 = 769, which is prime.


CROSSREFS

Cf. A000142, A001147, A116897.
Sequence in context: A179330 A066864 A181737 * A061062 A270141 A294349
Adjacent sequences: A116893 A116894 A116895 * A116897 A116898 A116899


KEYWORD

hard,more,nonn


AUTHOR

Giovanni Resta, Mar 04 2006


EXTENSIONS

5126 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008


STATUS

approved



