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Positive integers having the same number of base-3 runs of odd length as even.
1

%I #10 Jun 11 2019 17:47:49

%S 9,12,14,17,18,22,24,25,81,108,117,120,122,125,134,161,162,202,216,

%T 229,234,238,240,241,252,255,257,260,261,265,267,268,279,287,315,319,

%U 327,329,330,331,333,336,338,341,342,346,348,349

%N Positive integers having the same number of base-3 runs of odd length as even.

%H Robert Israel, <a href="/A044859/b044859.txt">Table of n, a(n) for n = 1..10000</a>

%p f:= proc(n) local L;

%p L:= [-1,op(convert(n,base,3)),-1];

%p L:= L[1..-2]-L[2..-1];

%p L:= select(t -> L[t]<>0, [$1..nops(L)]);

%p L:= L[2..-1]-L[1..-2];

%p convert(L mod 2, `+`)*2 = nops(L)

%p end proc:

%p select(f, [$1..1000]); # _Robert Israel_, Jun 11 2019

%K nonn,base

%O 1,1

%A _Clark Kimberling_