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%I #9 Feb 06 2017 14:37:50
%S 4,5,18,20,21,24,25,27,70,74,76,77,82,84,85,88,89,91,98,100,101,104,
%T 105,107,112,113,115,119,270,278,282,284,285,294,298,300,301,306,308,
%U 309,312,313,315,326,330,332,333,338,340,341,344,345,347,354,356,357
%N Nonnegative integers with an equal number of occurrences of all digits in bijective base-2 numeration.
%H Alois P. Heinz, <a href="/A258410/b258410.txt">Table of n, a(n) for n = 1..10000</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Bijective_numeration">Bijective numeration</a>
%e 4 = 12_bij2, 5 = 21_bij2, 18 = 1122_bij2, 20 = 1212_bij2.
%p p:= proc(n) local d, m, r; m:= n; r:= 0;
%p while m>0 do d:= irem(m, 2, 'm');
%p if d=0 then d:=2; m:= m-1 fi;
%p r:= r+x^d
%p od;
%p simplify(r/(x+x^2))::integer
%p end:
%p a:= proc(n) option remember; local k;
%p for k from 1+`if`(n=1, 0, a(n-1)) by 1
%p while not p(k) do od; k
%p end:
%p seq(a(n), n=1..70);
%Y Cf. A007931, A214676, A257869, A258411.
%K nonn,base
%O 1,1
%A _Alois P. Heinz_, May 29 2015
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