|
Search: id:A061860
|
|
| |
|
| 1, 2, 4, 11, 28, 152, 726, 5268, 40438, 365944, 3628810, 39974466, 479001612, 6228256404, 87178339984, 1307706805928, 20922789888016, 355688409760972, 6402373705728018, 121645133931170028, 2432902008232456692
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
Does this count some variety of necklaces?
|
|
FORMULA
|
a(n) = (1/n)*Sum_{d|n} phi(n/d)*C(n, d)*(d!)
|
|
MAPLE
|
[seq(A061860(j), j=1..40)]; with(numtheory); A061860 := proc(n) local d, s; s := 0; for d in divisors(n) do s := s + phi(n/d)*(binomial(n, d))*(d!); od; RETURN(s/n); end;
|
|
CROSSREFS
|
A061860[p] = A061417[p] = (p-1)!+(p-1) for all prime p's.
Sequence in context: A005200 A034768 A005503 this_sequence A093960 A118311 A132836
Adjacent sequences: A061857 A061858 A061859 this_sequence A061861 A061862 A061863
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Antti Karttunen May 11 2001
|
|
|
Search completed in 0.002 seconds
|
