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.

Showing 1-2 of 2 results.

A308708 Numbers k such that k^3 contains exactly three distinct digits; numbers with trailing zeros are excluded.

Original entry on oeis.org

5, 6, 8, 9, 14, 15, 36, 62, 92, 101, 173, 192, 211, 888, 1001, 3543, 10001, 100001, 110011, 146796, 1000001, 10000001, 100000001, 1000000001, 10000000001
Offset: 1

Views

Author

Andrej Jakobcic, Aug 01 2019

Keywords

Comments

10^k + 1 (A000533(k)) is a term for k >= 2. - Jinyuan Wang, Aug 02 2019

Examples

			a(8) = 62 because 62^3 = 238328, which contains exactly three distinct digits.
		

Crossrefs

Programs

  • Magma
    [k:k in [1..10000001]| k mod 10 ne 0 and  #Set(Intseq(k^3)) eq 3]; // Marius A. Burtea, Aug 02 2019
  • Mathematica
    Select[Range[10001], Mod[#, 10] > 0 && Length@ Union@ IntegerDigits[#^3] == 3 &] (* Giovanni Resta, Sep 05 2019 *)
  • PARI
    is(k) = #vecsort(digits(k^3), , 8)==3 && k%10!=0; \\ Jinyuan Wang, Aug 02 2019
    

Extensions

More terms from Jinyuan Wang, Aug 02 2019
a(23)-a(25) from Jon E. Schoenfield, Aug 02 2019

A385175 Cubes using at most three distinct digits, not ending in 0.

Original entry on oeis.org

1, 8, 27, 64, 125, 216, 343, 512, 729, 1331, 2744, 3375, 46656, 238328, 778688, 1030301, 5177717, 7077888, 9393931, 700227072, 1003003001, 44474744007, 1000300030001, 1000030000300001, 1331399339931331, 3163316636166336, 1000003000003000001, 1000000300000030000001, 1000000030000000300000001
Offset: 1

Views

Author

Gonzalo Martínez, Jun 20 2025

Keywords

Comments

This sequence has infinitely many terms since (10^m + 1)^3 is a term for all m >= 0.
Conjecture: a(26) = 3163316636166336 is the largest term with nonzero digits (See comments of A030294 and the data of A155146, where a(26) = A155146(47)^3).

Examples

			8, 343, and 46656 belong to this list because they are cubes that use 1, 2, and 3 distinct digits, respectively.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[10^6]^3,Length[Union[IntegerDigits[#]]]<4&&IntegerDigits[#][[-1]]!=0&] (* James C. McMahon, Jun 30 2025 *)
    fQ[n_] := Mod[n, 10] > 0 && Length@ Union@ IntegerDigits[n^3] < 4; k = 1; lst = {}; While[k < 1000002, If[ fQ@k, AppendTo[lst, k]]; k++]; lst^3 (* Robert G. Wilson v, Jul 10 2025 *)

Formula

a(n) = A202940(n)^3.

Extensions

a(28) from Robert G. Wilson v, Jul 10 2025
a(29) from David A. Corneth, Jul 10 2025
Showing 1-2 of 2 results.