OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..200
FORMULA
a(n) = A138177(2n,n).
EXAMPLE
a(2) = 7:
[1 1] [2 1] [0 1] [2 0] [0 2] [3 0] [1 0]
[1 1] [1 0] [1 2] [0 2] [2 0] [0 1] [0 3].
MAPLE
gf:= k-> 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)):
A:= (n, k)-> coeff(series(gf(k), x, n+1), x, n):
a:= n-> add(A(2*n, n-j)*(-1)^j*binomial(n, j), j=0..n):
seq(a(n), n=0..20);
MATHEMATICA
gf[k_] := 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)); A[n_, k_] := SeriesCoefficient[ gf[k], {x, 0, n}]; a[n_] := Sum[A[2*n, n-j]*(-1)^j*Binomial[n, j], {j, 0, n}]; Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Feb 25 2017, translated from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 31 2016
STATUS
approved