OFFSET
1,3
FORMULA
a(n) ~ c*phi^n, where phi is the golden ratio (A001622) and c = 1.83226227102725... (conjecture).
MATHEMATICA
a[n_] := a[n] = Sum[a[i], {i, Divisors[n - 1]}] + Sum[a[j], {j, Divisors[n - 2]}]; a[1] = a[2] = 1; Table[a[n], {n, 1, 40}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Oct 13 2017
STATUS
approved