cp's OEIS Frontend

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.

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A136836 Numbers k such that k and k^2 use only the digits 0, 1, 2 and 9.

Original entry on oeis.org

0, 1, 10, 11, 100, 101, 110, 1000, 1001, 1010, 1011, 1100, 1101, 10000, 10001, 10010, 10011, 10100, 10110, 11000, 11001, 11010, 100000, 100001, 100010, 100011, 100100, 100101, 100110, 101000, 101001, 101100, 110000, 110001, 110010, 110100, 1000000, 1000001, 1000010, 1000011, 1000100
Offset: 1

Views

Author

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008

Keywords

Comments

Generated with DrScheme.
Comparison of b-files indicates that the first difference from A136831 is at the 1262nd entry. - R. J. Mathar Apr 29 2008
More precisely, A278038(18) = 10101, A136827(294) = 10110001101 resp. A136808(1262) = A136831(1262) = 101100000000000 are the first terms from where on these four sequences differ from the present one; a(1262) = 101090009991101 is also the first term containing a digit > 1. - M. F. Hasler, Nov 15 2017

Examples

			101090009991101^2 = 10219190120000900002099192201.
		

Crossrefs

Cf. A136808, A136809, A136810, ..., A137147 for other digit combinations.
See also A058412 = A058411^2: squares having only digits {0,1,2}, A277946 = A277959^2 = squares whose largest digit is 2.
The first 1261 terms are also a subsequence of A278038 (binary numbers without '111'), in turn a subsequence of the binary numbers A007088.

Programs

  • Mathematica
    With[{c={0,1,2,9}},Select[FromDigits/@Tuples[c,7],SubsetQ[c,IntegerDigits[#^2]]&]] (* Harvey P. Dale, Feb 11 2024 *)

A295017 Squares whose largest digit is 7.

Original entry on oeis.org

576, 676, 1764, 2704, 3721, 4761, 5476, 5776, 6724, 7056, 7225, 7744, 15376, 17161, 17424, 20736, 23716, 27225, 27556, 30276, 32761, 35721, 37636, 47524, 50176, 51076, 54756, 57121, 57600, 67600, 70225, 70756, 72361, 73441, 75076, 75625, 76176, 101761, 106276, 126736, 137641, 141376
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Crossrefs

Cf. A295007 (square roots of the terms), A277946 .. A277948 (same for digit 2 .. 4), A295015 .. A295019 (same for digit 5 .. 9), A295022 (same for cubes).
Cf. A000290 (the squares).

Programs

  • Mathematica
    Select[Range[1000]^2,Max[IntegerDigits[#]]==7&] (* Harvey P. Dale, Dec 15 2024 *)
  • PARI
    is_A295017(n)=issquare(n)&&n&&vecmax(digits(n))==7 \\ The "n&&" avoids an error message for n=0.

Formula

a(n) = A295007(n)^2.
Previous Showing 11-12 of 12 results.