

A298702


Numbers k such that k!+1 reversed is a prime.


1



1, 2, 3, 6, 11, 15, 17, 19, 22, 51, 867, 1909, 9641
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OFFSET

1,2


COMMENTS

a(14) > 19200, if it exists.  Giovanni Resta, May 04 2018


LINKS

Table of n, a(n) for n=1..13.


MATHEMATICA

Do[If[PrimeQ[FromDigits[Reverse[IntegerDigits[n! + 1]]]], Print[n]], {n, 400}] (* Vincenzo Librandi, Jan 25 2018 *)


PROG

(PARI) isok(n) = isprime(fromdigits(Vecrev(digits(n!+1)))); \\ Michel Marcus, Jan 26 2018


CROSSREFS

Cf. A002981.
Sequence in context: A163781 A090304 A005211 * A076307 A102990 A138519
Adjacent sequences: A298699 A298700 A298701 * A298703 A298704 A298705


KEYWORD

nonn,base,more


AUTHOR

Paolo Galliani, Jan 25 2018


EXTENSIONS

a(1)a(3) and a(8)a(10) from Vincenzo Librandi, Jan 25 2018
a(11)a(12) from Paolo Galliani, May 02 2018
a(13) from Giovanni Resta, May 04 2018


STATUS

approved



