OFFSET
0,4
COMMENTS
Shifts 2 places left under 4th-order binomial transform.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..516
FORMULA
a(0) = a(1) = 1; a(n) = Sum_{k=0..n-2} binomial(n-2,k) * 4^k * a(n-k-2).
MATHEMATICA
nmax = 22; A[_] = 0; Do[A[x_] = 1 + x + x^2 A[x/(1 - 4 x)]/(1 - 4 x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[0] = a[1] = 1; a[n_] := a[n] = Sum[Binomial[n - 2, k] 4^k a[n - k - 2], {k, 0, n - 2}]; Table[a[n], {n, 0, 22}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 30 2022
STATUS
approved