|
Search: id:A130648
|
|
|
| A130648 |
|
Number of degree-n permutations without even cycles and such that number of cycles of size 2k-1 is odd (or zero) for every k. |
|
+0
1
|
|
| 1, 1, 0, 3, 8, 25, 184, 721, 9904, 66753, 691088, 5973121, 84925048, 940427137, 12801319816, 186556383105, 3174772979936, 48489077948161, 842173637012896, 15359492773456129, 316965131969908072, 6368424993521096961
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
FORMULA
|
E.g.f.: Product_{k>0} (1+sinh(x^(2*k-1)/(2*k-1))).
|
|
EXAMPLE
|
a(3)=3 because we have (1)(2)(3), (123), and (132).
|
|
MAPLE
|
g:=product(1+sinh(x^(2*k-1)/(2*k-1)), k=1..30): gser:=series(g, x=0, 27): seq(factorial(n)*coeff(gser, x, n), n=0..24); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 24 2007
|
|
CROSSREFS
|
Cf. A060307.
Sequence in context: A004205 A097713 A009392 this_sequence A061812 A009452 A148801
Adjacent sequences: A130645 A130646 A130647 this_sequence A130649 A130650 A130651
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 11 2007
|
|
EXTENSIONS
|
More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 24 2007
|
|
|
Search completed in 0.003 seconds
|
