1,2

a(n) = 2*a(n-1)+2*a(n-2)-a(n-3).

a(n) = -2*A121646(n+1).

c[i_, k_] := Floor[Mod[i/2^k, 2]] b[i_, k_] := If[c[i, k] == 0 && c[ i, k + 1] == 0, 0, If[c[i, k] == 1 && c[i, k + 1] == 1, 0, 1]] n = 4 - 1; M = Table[If[Sum[b[i, k]*b[j, k], {k, 0, n}] == 0, 1, 0], {j, 0, n}, {i, 0, n}] v[1] = {0, 1, 2, 3} v[n_] := v[n] = M.v[n - 1] a = Table[Floor[v[n][[1]]], {n, 1, 50}] Det[M - x*IdentityMatrix[4]] Factor[%] aaa = Table[x /. NSolve[Det[M - x*IdentityMatrix[4]] == 0, x][[n]], {n, 1, 4}] Abs[aaa] a1 = Table[N[a[[n]]/a[[n - 1]]], {n, 7, 50}]

Sequence in context: A163478 A130440 A137272 this_sequence A032740 A167330 A025629

Adjacent sequences: A121798 A121799 A121800 this_sequence A121802 A121803 A121804

nonn

Roger Bagula and Gary Adamson (rlbagulatftn(AT)yahoo.com), Aug 27 2006

Edited by the Associate Editors of the OEIS, Aug 18 2009