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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A137144 Numbers k such that k and k^2 use only the digits 4, 6, 7 and 8.

Original entry on oeis.org

8, 88, 8874, 68474, 86478
Offset: 1

Views

Author

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

Keywords

Comments

Generated with DrScheme.
No further terms up to and including 1000000. - Harvey P. Dale, Dec 03 2010
No further terms <= 10^40. - Michael S. Branicky, Feb 12 2024
From Pontus von Brömssen, May 01 2024: (Start)
a(6) > 6*10^46 (if it exists).
If k = x*10^m is a term where 1 < x < 10 and k is not 88 or 8874, then 20/3 < x < 8.7674847468864688448864887688468686674647846475.
(End)

Examples

			86478^2 = 7478444484.

Links

Crossrefs

Cf. A077439, A136809, A136813, A136985, A137028, A137105, A137147.

Programs

  • Mathematica
    clearQ[n_]:=Module[{dc=DigitCount[n]},dc[[1]]==dc[[2]]==dc[[3]]==dc[[5]]==dc[[9]]==dc[[10]]==0]
Select[Range[1000000],clearQ[#]&&clearQ[#^2]&] (* Harvey P. Dale, Dec 03 2010 *)
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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