login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A091529 When sum {k=1 to n} H(k) k! (n-k)! (mod {n+1}) (A091528) is not zero. 2
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois Alcover, May 22 2014 *)

CROSSREFS

Cf. A091528.

Sequence in context: A143028 A277018 A277008 * A184967 A267137 A095775

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 31 19:37 EDT 2020. Contains 333151 sequences. (Running on oeis4.)