A239827 - OEIS

%I #8 Mar 27 2014 18:40:15

%S 0,105,205,305,11014,11023,11041,11059,12017,12021,12046,12075,12079,

%T 13027,13031,13096,14011,14018,14043,14068,14075,14082,16019,16022,

%U 16044,16072,16075,17012,17091,17094,18014,18039,18075,18086,19016,19029,19037,19058

%N Cyclops numbers whose squares are cyclops numbers.

%C Subsequence of A239589.

%H Giovanni Resta, <a href="/A239827/b239827.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = sqrt(A239828(n)).

%e 12046 is in the sequence because 12046^2 = 145106116, and both 12406 and 145106116 are cyclops numbers.

%o (PARI)

%o is_cyclops(k) = {

%o   if(k==0, return(1));

%o   my(d=digits(k), j);

%o   if(#d%2==0 || d[#d\2+1]!=0, return(0));

%o   for(j=1, #d\2, if(d[j]==0, return(0)));

%o   for(j=#d\2+2, #d, if(d[j]==0, return(0)));

%o   return(1)}

%o s=[]; for(n=0, 100000, if(is_cyclops(n) && is_cyclops(n^2), s=concat(s, n))); s

%Y Cf. A134808, A239589, A239828.

%K nonn,base

%O 1,2

%A _Colin Barker_, Mar 27 2014