|
| |
|
|
A361283
|
|
Expansion of e.g.f. exp(x/(1-x)^4).
|
|
4
|
|
|
|
1, 1, 9, 85, 961, 13041, 207001, 3746149, 75832065, 1693615681, 41302616041, 1090835399061, 30988423000129, 941461990360945, 30439632977968761, 1042973073239321701, 37731609890300935681, 1436586994020158747649
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
|
|
|
FORMULA
|
a(n) = n! * Sum_{k=0..n} (-1)^(n-k) * binomial(-4*k,n-k)/k! = n! * Sum_{k=0..n} binomial(n+3*k-1,n-k)/k!.
a(0) = 1; a(n) = (n-1)! * Sum_{k=1..n} (-1)^(k-1) * k * binomial(-4,k-1) * a(n-k)/(n-k)!.
D-finite with recurrence a(n) +(-5*n+4)*a(n-1) +(n-1)*(10*n-23)*a(n-2) -10*(n-1)*(n-2)*(n-3)*a(n-3) +5*(n-1)*(n-2)*(n-3)*(n-4)*a(n-4) -(n-5)*(n-1)*(n-2)*(n-3)*(n-4)*a(n-5)=0. - R. J. Mathar, Mar 12 2023
a(n) ~ 2^(1/5) * n^(n - 1/10) * exp(-27/1280 - 13*2^(3/5)*n^(1/5)/800 + 13*2^(1/5)*n^(2/5)/240 + 2^(-6/5)*n^(3/5) + 5*2^(-8/5)*n^(4/5) - n) / sqrt(5) * (1 + 116303*2^(12/5)/(3200000*n^(1/5))). - Vaclav Kotesovec, Nov 11 2023
|
|
|
MAPLE
|
n!*add(binomial(n+3*k-1, n-k)/k!, k=0..n) ;
end proc:
|
|
|
PROG
|
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x/(1-x)^4)))
(PARI) a(n) = n!*sum(k=0, n, (-1)^(n-k)*binomial(-4*k, n-k)/k!);
(PARI) a(n) = n!*sum(k=0, n, binomial(n+3*k-1, n-k)/k!);
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=(i-1)!*sum(j=1, i, (-1)^(j-1)*j*binomial(-4, j-1)*v[i-j+1]/(i-j)!)); v;
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
