OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (14,-91,364,-1001,2002,-3003,3432,-3003,2002,-1001,364,-91,14,-1).
FORMULA
From Amiram Eldar, Aug 30 2022: (Start)
Sum_{n>=0} 1/a(n) = 990*Pi^2 - 38297957/3920.
Sum_{n>=0} (-1)^n/a(n) = 15*Pi^2 - 12288*log(2)/7 + 4193253/3920. (End)
EXAMPLE
If n=0 then C(0+4,4)*C(0+9,0+0)= C(4,4)*C(9,0)=1*1=1
If n=6 then C(6+4,4)*C(6+9,6+0)= C(10,4)*C(15,6)=210*5005=1051050
MATHEMATICA
Table[Binomial[n+4, 4]Binomial[n+9, n], {n, 0, 20}] (* Harvey P. Dale, Nov 15 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Zerinvary Lajos, Apr 22 2005
EXTENSIONS
More terms from Harvey P. Dale, Nov 15 2018
STATUS
approved