login
A239827
Cyclops numbers whose squares are cyclops numbers.
3
0, 105, 205, 305, 11014, 11023, 11041, 11059, 12017, 12021, 12046, 12075, 12079, 13027, 13031, 13096, 14011, 14018, 14043, 14068, 14075, 14082, 16019, 16022, 16044, 16072, 16075, 17012, 17091, 17094, 18014, 18039, 18075, 18086, 19016, 19029, 19037, 19058
OFFSET
1,2
COMMENTS
Subsequence of A239589.
LINKS
FORMULA
a(n) = sqrt(A239828(n)).
EXAMPLE
12046 is in the sequence because 12046^2 = 145106116, and both 12406 and 145106116 are cyclops numbers.
PROG
(PARI)
is_cyclops(k) = {
if(k==0, return(1));
my(d=digits(k), j);
if(#d%2==0 || d[#d\2+1]!=0, return(0));
for(j=1, #d\2, if(d[j]==0, return(0)));
for(j=#d\2+2, #d, if(d[j]==0, return(0)));
return(1)}
s=[]; for(n=0, 100000, if(is_cyclops(n) && is_cyclops(n^2), s=concat(s, n))); s
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Colin Barker, Mar 27 2014
STATUS
approved