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%I #8 Feb 06 2017 14:38:17
%S 5,9,17,33,41,42,65,74,77,84,85,90,129,138,145,146,148,162,166,168,
%T 173,180,257,266,274,276,279,282,285,292,296,297,301,307,310,322,324,
%U 330,332,336,341,345,349,354,360,513,522,530,532,538,545,546,548,552,562
%N Nonnegative integers n such that in bijective base-2 numeration the number of occurrences of each digit doubles when n is squared.
%H Alois P. Heinz, <a href="/A258411/b258411.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 5 = 21_bij2 and 5^2 = 25 = 2121_bij2, 42 = 12122_bij2 and 42^2 = 1764 = 2122211212_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; r
%p end:
%p a:= proc(n) option remember; local k;
%p for k from 1+`if`(n=1, 0, a(n-1))
%p while p(k)*2<>p(k^2) do od; k
%p end:
%p seq(a(n), n=1..60);
%Y Cf. A007931, A214676, A257867, A258410.
%K nonn,base
%O 1,1
%A _Alois P. Heinz_, May 29 2015
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