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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 17 15:32 EST 2020. Contains 331998 sequences. (Running on oeis4.)