A076379 n!-x!+1 is never prime for x<n.

1, 15, 22, 27, 28, 36, 43, 45, 48, 50, 52, 58, 60, 63, 64, 67, 70, 77, 80, 82, 83, 84, 85, 86, 97, 104, 110, 113, 120, 124, 125, 129, 131, 135, 136, 138, 140, 147, 158, 161, 164, 171, 173, 174, 183, 185, 189, 192, 195, 199

Offset

1,2

Links

Table of n, a(n) for n=1..50.

Mathematica

Select[Range[200], NoneTrue[Table[#!-x!+1, {x, #-1}], PrimeQ]&] (* Harvey P. Dale, Sep 12 2022 *)

Prog

(PARI) for (a=1, 100, c=0; for (b=1, a-1, if (b%2<>a%2, continue); if (isprime(a!-b!+1), c=1; break)); if (c==0, print1(a, ", ")))

Crossrefs

Cf. A076378.

Sequence in context: A115174 A092783 A108638 * A227095 A038753 A006615

Adjacent sequences: A076376 A076377 A076378 * A076380 A076381 A076382

Keyword

nonn

Author

Jon Perry, Oct 08 2002

Extensions

More terms from Harvey P. Dale, Sep 12 2022

Status

approved