A390509 - OEIS

%I #7 Dec 17 2025 20:07:33

%S 1,18,27,30,31,32,35,37,43,46,47,61,63,65,79,93,306,450,459,462,498,

%T 523,526,530,535,536,538,539,542,559,571,578,587,590,607,608,611,613,

%U 619,622,623,631,632,634,635,706,715,718,754,779,782,815,827,899,901

%N Indices k such that (number of 0's) = (number of 1's) in the NA-run 01-word indexed by a(k) in A390508(k).

%e a(18) = 010110, in which there are 3 0's and 3 1's, so 18 is in the list.

%t g[w_] := StringJoin[Map[ToString[#[[1]]] <> IntegerString[Length[#], 2] &, Split[Characters[w]]]];

%t s[n_] := Map[StringJoin[Map[ToString, Rest[IntegerDigits[#, 2]]]] &, Range[2, 2^(n + 1) - 1]];

%t m = Map[g, s[11]];

%t m1 = ToExpression /@ Characters /@ m;

%t Select[Range[Length[m1]], Count[m1[[#]], 0] == Count[m1[[#]], 1] &]

%t (* _Peter J. C. Moses_, Nov 05 2025 *)

%Y Cf. A390508.

%K nonn

%O 1,2

%A _Clark Kimberling_, Dec 08 2025