A018828 Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10).

0, 1, 4, 16, 41, 54, 64, 164, 165, 256, 290, 487, 545, 566, 1024, 1160, 1948, 2180, 3546, 4096, 4226, 4261, 7625, 8321, 8720, 9514, 13813, 13867, 15913, 16158, 16384, 16904, 33284, 46126, 54854, 55468, 63652, 64632, 65536, 66050, 67616, 113047, 130591

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Crossrefs

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).

Programs

Mathematica

Select[Range[0,150000],SequenceCount[IntegerDigits[#^2,4],IntegerDigits[#,4]]>0&] (* Harvey P. Dale, Aug 13 2023 *)

Extensions

Definition clarified by Harvey P. Dale, Aug 13 2023