|
|
A052667
|
|
E.g.f. 1/(1-2x-x^4).
|
|
0
|
|
|
1, 2, 8, 48, 408, 4320, 54720, 806400, 13587840, 257644800, 5428684800, 125817753600, 3181049625600, 87128475033600, 2570016024576000, 81222270345216000, 2738060898693120000, 98070849049485312000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
E.g.f.: -1/(-1+2*x+x^4)
Recurrence: {a(0)=1, a(1)=2, a(2)=8, a(3)=48, (-n^4-35*n^2-50*n-24-10*n^3)*a(n)+(-2*n-8)*a(n+3)+a(n+4)=0}
Sum(1/86*(27+18*_alpha^3+12*_alpha^2+8*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+2*_Z+_Z^4))*n!
|
|
MAPLE
|
spec := [S, {S=Sequence(Union(Z, Z, Prod(Z, Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
STATUS
|
approved
|
|
|
|