A239827 Cyclops numbers whose squares are cyclops numbers.

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

Giovanni Resta, Table of n, a(n) for n = 1..10000

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

Cf. A134808, A239589, A239828.

Sequence in context: A347881 A044337 A044718 * A273521 A214082 A069692

Adjacent sequences: A239824 A239825 A239826 * A239828 A239829 A239830

Keyword

nonn,base

Author

Colin Barker, Mar 27 2014

Status

approved