A239589 - OEIS

%I #13 Jun 25 2022 11:59:59

%S 0,105,138,145,155,179,195,205,217,226,241,243,255,257,259,274,295,

%T 305,1054,1068,1082,1091,1114,1127,1136,1158,1162,1175,1192,1196,1221,

%U 1229,1233,1237,1261,1269,1273,1277,1281,1308,1323,1327,1338,1364,1375,1386

%N Numbers whose squares are cyclops numbers.

%H Colin Barker, <a href="/A239589/b239589.txt">Table of n, a(n) for n = 1..4000</a>

%e 138 is in the sequence because 138^2 = 19044, which is a cyclops number.

%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, 2000, if(is_cyclops(n^2), s=concat(s, n))); s

%Y Cf. A000290, A134808, A160711, A239587, A239588, A239590, A239591.

%K nonn,base

%O 1,2

%A _Colin Barker_, Mar 24 2014