A137116 Numbers k such that k and k^2 use only the digits 2, 5, 7, 8 and 9.
5, 27, 77, 85, 527, 727, 7227, 9777, 28277, 29585, 88277, 99277, 278527, 298827, 2788527, 2789227, 5289227, 8875727, 9889277, 22925527, 27797977, 29879585, 52898827, 85298827, 88875527, 99789227, 99988777, 278889277, 287279585, 292898827, 297875527, 299929585, 527252527, 528982977, 727528527, 727825527, 727925527, 988579585, 992587527
Offset: 1
Examples
727872928279585^2 = 529798999722297889227927772225.
Links
- Michael S. Branicky, Table of n, a(n) for n = 1..578 (through 20 digits; first 180 terms from Jonathan Wellons)
- Jonathan Wellons, Tables of Shared Digits [archived].
Programs
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Python
# uses auptod in A137110 print(auptod(16, only="25789")) # Michael S. Branicky, May 27 2021
Comments