OFFSET
0,2
LINKS
FORMULA
E.g.f.: (1+36*x+216*x^2+336*x^3+126*x^4)/(1-x)^14.
a(n) = A062138(n+4, 4).
a(n) = (n+4)!*binomial(n+9, 9)/4!.
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..k} binomial(k,j) * Stirling1(n,k) * Stirling2(j,i) * x^(k-j) then a(n-9) = (-1)^(n-1)*f(n,9,-5), (n>=9). - Milan Janjic, Mar 01 2009
EXAMPLE
a(2) = (2+4)! * binomial(2+9,9) / 4! = (720 * 55)/ 24 = 1650. - Indranil Ghosh, Feb 24 2017
MATHEMATICA
Table[(n+4)!*Binomial[n+9, 9]/4!, {n, 0, 15}] (* Indranil Ghosh, Feb 24 2017 *)
PROG
(PARI) a(n) = (n+4)!*binomial(n+9, 9)/4! \\ Indranil Ghosh, Feb 24 2017
(Python)
import math
f=math.factorial
def C(n, r):return f(n)/f(r)/f(n-r)
def A062151(n): return f(n+4)*C(n+9, 9)/f(4) # Indranil Ghosh, Feb 24 2017
(Magma) [Factorial(n+4)*Binomial(n+9, 9)/Factorial(4): n in [0..20]]; // G. C. Greubel, May 12 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jun 19 2001
STATUS
approved