A281228 - OEIS

A281228

Expansion of (Sum_{k>=0} x^(3^k))^2 [even terms only].

0, 1, 2, 1, 0, 2, 2, 0, 0, 1, 0, 0, 0, 0, 2, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

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OFFSET

0,3

COMMENTS

Number of ways to write 2n as an ordered sum of two powers of 3.

First bisection of self-convolution of characteristic function of powers of 3.

LINKS

Table of n, a(n) for n=0..105.

Index entries for sequences related to compositions

FORMULA

G.f.: (Sum_{k>=0} x^(3^k))^2 [even terms only].

EXAMPLE