|
| |
| |
|
|
|
8, 114, 667, 2504, 7191, 17266, 36482, 70050, 124882, 209834, 335949, 516700, 768233, 1109610, 1563052, 2154182, 2912268, 3870466, 5066063, 6540720, 8340715, 10517186, 13126374, 16229866, 19894838, 24194298, 29207329
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,1
|
|
|
REFERENCES
|
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(2.3.14).
|
|
|
LINKS
|
Table of n, a(n) for n=0..26.
|
|
|
FORMULA
|
G.f.: (x+2)*(2*x^4+8*x^3+36*x^2+31*x+4)/(1-x)^6. Generally, g.f. for k-th column of A046741 is coefficient of y^k in expansion of (1-y)/((1-y-y^2)*(1-y)-(1+y)*x).
|
|
|
CROSSREFS
|
Cf. dumbbells: A002940, A002941, A002889, A046741, A055608, A062123-A062127.
Sequence in context: A099715 A023814 A217772 * A222520 A220635 A113670
Adjacent sequences: A062123 A062124 A062125 * A062127 A062128 A062129
|
|
|
KEYWORD
|
easy,nonn,changed
|
|
|
AUTHOR
|
Vladeta Jovovic, Jun 04 2001
|
|
|
EXTENSIONS
|
More terms from Larry Reeves (larryr(AT)acm.org), Jun 06 2001
|
|
|
STATUS
|
approved
|
| |
|
|
