A342638 - OEIS

A342638

a(0) = 0, a(1) = 1; a(2*n) = a(n), a(2*n+1) = 9*a(n) + a(n+1).

0, 1, 1, 10, 1, 19, 10, 91, 1, 28, 19, 181, 10, 181, 91, 820, 1, 37, 28, 271, 19, 352, 181, 1639, 10, 271, 181, 1720, 91, 1639, 820, 7381, 1, 46, 37, 361, 28, 523, 271, 2458, 19, 523, 352, 3349, 181, 3268, 1639, 14761, 10, 361, 271, 2620, 181, 3349, 1720, 15571, 91, 2458, 1639, 15571, 820

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OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..16384

FORMULA

G.f.: x * Product_{k>=0} (1 + x^(2^k) + 9*x^(2^(k+1))).

MAPLE

a:= proc(n) option remember; `if`(n<2, n, (q->

`if`(d=1, 9*a(q)+a(q+1), a(q)))(iquo(n, 2, 'd')))

end:

seq(a(n), n=0..60); # Alois P. Heinz, Mar 17 2021