OFFSET
0,4
FORMULA
Recurrence: a(n+1) = Sum_{k=0..n} binomial(n+k,2*k+1)*a(k).
MATHEMATICA
terms = 26; A[_] = 0; Do[A[x_] = 1 + x (1 + x A[x/(1 - x)^2]/(1 - x)^2) + O[x]^(terms + 1) // Normal, terms + 1]; CoefficientList[A[x], x]
a[n_] := a[n] = Sum[Binomial[n + k - 1, 2 k + 1] a[k], {k, 0, n - 1}]; a[0] = 1; a[1] = 1; Table[a[n], {n, 0, 26}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 02 2019
STATUS
approved