A044934 - OEIS

A044934

Number of runs of even length in the base 3 representation of n.

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

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OFFSET

1,36

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

f:= proc(n) local L, d, R;

L:= convert(n, base, 3);

d:= nops(L);

R:= select(t -> (t=1) or (t=d+1) or (L[t] <> L[t-1]), [$1..d+1]);

R:= R[2..-1] - R[1..-2];

nops(select(type, R, even))