A108948 Numbers n such that (n!/n#)^2 + 1 is prime, where n# = primorial numbers (A034386).

1, 2, 3, 4, 5, 6, 7, 12, 13, 22, 23, 39, 50, 54, 60, 61, 69, 182, 620, 767, 1308, 5129

Offset

1,2

Comments

n!/n# is known as n compositorial. All values have been proved prime. Primality proof for the largest, which has 29223 digits: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing (5129!/5129#)^2+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 2591 Calling Brillhart-Lehmer-Selfridge with factored part 33.59% (5129!/5129#)^2+1 is prime! (164.5911s+0.0122s)

Links

Table of n, a(n) for n=1..22.

Crossrefs

Sequence in context: A028819 A234841 A353725 * A107818 A039952 A129978

Adjacent sequences: A108945 A108946 A108947 * A108949 A108950 A108951

Keyword

more,nonn

Author

Jason Earls, Jul 21 2005

Status

approved