A123186 a(3*n-2) = a(3*n-1) = a(3*n) = b(n), where b(1) = 1, b(2) = -2, b(3) = 0, and b(n+1) = -(m+1)*b(n) - (m-1)*(m-2)*b(n-1) - (m-3)*(m-4)*(m-5)*b(n-2) for m = 3*n.

1, 1, 1, -2, -2, -2, 0, 0, 0, -8, -8, -8, 1112, 1112, 1112, -16336, -16336, -16336, 29760, 29760, 29760, 108608, 108608, 108608, 112587520, 112587520, 112587520, -3584451200, -3584451200, -3584451200, 17790850560, 17790850560, 17790850560, 208254684160, 208254684160

Offset

1,4

Links

Table of n, a(n) for n=1..35.

Mathematica

M1 = {{-n, 1, 0}, {0, 1, 0}, {0, 0, 1}};
M2 = {{1, 0, 0}, {n, -n, 1}, {0, 0, 1}};
M3 = {{1, 0, 0}, {0, 1, 0}, {0, n, -n}};
M[n_] := If[Mod[n, 3] == 1, M1, If[Mod[n, 3] == 2, M2, M3]]
v[1] = {1, 0, 0}
v[n_] := v[n] = M[n].v[n - 1]
a1 = Table[v[n][[1]], {n, 1, 50}]

Crossrefs

Sequence in context: A039967 A258133 A327152 * A127323 A327298 A132896

Adjacent sequences: A123183 A123184 A123185 * A123187 A123188 A123189

Keyword

sign,easy,less

Author

Roger L. Bagula and Gary W. Adamson, Oct 03 2006

Extensions

Meaningful name by Dominic McCarty, Jul 01 2025

Status

approved