A091529 When sum {k=1 to n} H(k) k! (n-k)! (mod {n+1}) (A091528) is not zero.

1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 16, 18, 21, 22, 25, 28, 30, 33, 36, 37, 40, 42, 45, 46, 52, 57, 58, 60, 61, 66, 70, 72, 73, 78, 81, 82, 85, 88, 93, 96, 100, 102, 105, 106, 108, 112, 117, 121, 126, 130, 133, 136, 138, 141, 145, 148, 150, 156, 157, 162, 165, 166, 172, 177

Offset: 1

Author

Leroy Quet, Jan 08 2004

Keywords

• nonn

Comments

It is conjectured that the density decreases. In each century the number of members are so far: 41, 30, 26, 28, 23, 24, 24, 21, 24, 22, ...

Crossrefs

Cf. A091528.

Programs

Mathematica

Select[ Range[178], Mod[ Sum[ HarmonicNumber[k] k! (# - k)!, {k, 1, #}], # + 1] != 0 &] (* Robert G. Wilson v, Jan 14 2004; corrected by Jean-François Alcover, May 22 2014 *)

Extensions

Extended by Robert G. Wilson v, Jan 14 2004