

A204658


Numbers n such that n!101 is prime.


8



3, 4, 6, 8, 12, 20, 40, 48, 60, 62, 70, 84, 88, 168, 240, 258, 372, 760, 932, 1010, 2110, 2464, 2490, 2702, 3180, 4744, 6024, 8858, 9060, 10322, 13382, 15778, 19322, 22372, 22928, 25344, 28050, 40604, 42282, 45884, 52428, 58250, 81220, 93612, 108650
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OFFSET

1,1


COMMENTS

n!10 = product( n10k, 0 <= k < n/10 ).
See also links in A156165.
a(1)a(40) are proved prime by deterministic tests of pfgw.  Robert Price, Jun 11 2012
a(41) > 50000.  Robert Price, Jun 11 2012


LINKS

Table of n, a(n) for n=1..45.
Ken Davis, Status of Search for Multifactorial Primes.
Ken Davis, Results for n!101.


MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n  k, k]];
Select[Range[1000], PrimeQ[MultiFactorial[#, 10]  1] & ] (* Robert Price, Apr 19 2019 *)


PROG

(PARI) for(n=0, 9999, isprime(prod(i=0, (n2)\10, n10*i)1)& print1(n", "))


CROSSREFS

Cf. A204657, A204659, A204660, A204661, A204662, A204663, A204664, A156165, A156167, A085150, A085148, A085146, A037083, A080778, A002981.
Sequence in context: A145751 A277099 A146566 * A139041 A244607 A136483
Adjacent sequences: A204655 A204656 A204657 * A204659 A204660 A204661


KEYWORD

nonn,hard


AUTHOR

M. F. Hasler, Jan 17 2012


EXTENSIONS

a(26)a(40) from Robert Price, Jun 11 2012
a(41)a(45) from Ken Davis link entered by Robert Price, Apr 19 2019


STATUS

approved



