This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A018828 #13 Apr 04 2024 10:07:16 %S A018828 0,1,4,16,41,54,64,164,165,256,290,487,545,566,1024,1160,1948,2180, %T A018828 3546,4096,4226,4261,7625,8321,8720,9514,13813,13867,15913,16158, %U A018828 16384,16904,33284,46126,54854,55468,63652,64632,65536,66050,67616,113047,130591 %N A018828 Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10). %t A018828 Select[Range[0,150000],SequenceCount[IntegerDigits[#^2,4],IntegerDigits[#,4]]>0&] (* _Harvey P. Dale_, Aug 13 2023 *) %Y A018828 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 A018828 nonn,base %O A018828 1,3 %A A018828 _David W. Wilson_ %E A018828 Definition clarified by _Harvey P. Dale_, Aug 13 2023