OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..500
FORMULA
a(n) = Sum_{m >= 0} binomial(binomial(m, n), 3)/2^(m+1).
MAPLE
A126086 := proc(n) local x, y, z ; coeftayl(coeftayl(coeftayl(1/(1-x-y-z-x*y-x*z-y*z-x*y*z), z=0, n), y=0, n), x=0, n) ; end: A001850 := proc(n) local k ; add(binomial(n, k)*binomial(n+k, k), k=0..n) ; end: A137219 := proc(n) (A126086(n)-3*A001850(n)+2)/6 ; end: seq(A137219(n), n=1..30) ; # R. J. Mathar, Apr 01 2008
MATHEMATICA
PROG
(Sage)
def A137219(n): return round( sum( binomial(binomial(j, n), 3)/2^(j+1) for j in (0..1000) ) )
[A137219(n) for n in (1..30)] # G. C. Greubel, Jan 05 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Mar 06 2008, Mar 16 2008
EXTENSIONS
More terms from R. J. Mathar, Apr 01 2008
STATUS
approved