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

1,2

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, ...

Links

Table of n, a(n) for n=1..64.

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 *)

Crossrefs

Cf. A091528.

Sequence in context: A277018 A277008 A354912 * A184967 A141820 A267137

Adjacent sequences: A091526 A091527 A091528 * A091530 A091531 A091532

Keyword

nonn

Author

Leroy Quet, Jan 08 2004

Extensions

Extended by Robert G. Wilson v, Jan 14 2004

Status

approved