A018828 - OEIS

A018828

Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10).

%I #13 Apr 04 2024 10:07:16

%S 0,1,4,16,41,54,64,164,165,256,290,487,545,566,1024,1160,1948,2180,

%T 3546,4096,4226,4261,7625,8321,8720,9514,13813,13867,15913,16158,

%U 16384,16904,33284,46126,54854,55468,63652,64632,65536,66050,67616,113047,130591

%N Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10).

%t Select[Range[0,150000],SequenceCount[IntegerDigits[#^2,4],IntegerDigits[#,4]]>0&] (* _Harvey P. Dale_, Aug 13 2023 *)

%Y Cf. A018826 (base 2), A018827 (base 3), A018829 (base 5), A018830 (base 6), A018831 (base 7), A018832 (base 8), A018833 (base 9), A018834 (base 10).

%K nonn,base

%O 1,3

%A _David W. Wilson_

%E Definition clarified by _Harvey P. Dale_, Aug 13 2023