A244960 Smallest positive multiple of n whose base 9 representation contains only 0's and 1's.
1, 10, 9, 820, 10, 90, 91, 5380840, 9, 10, 7381, 7380, 91, 66430, 90, 43644592, 6562, 90, 7372, 820, 819, 65692, 7291, 48427560, 7300, 66430, 81, 532252, 59131, 90, 66340, 48368512, 66429, 6562, 66430, 7380, 532171, 7372, 819, 5380840, 82, 597870, 66349
Offset: 1
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
- Ed Pegg Jr., 'Binary' Puzzle
- Eric M. Schmidt, Sage code to compute this sequence (use b=9)
- Chai Wah Wu, Pigeonholes and repunits, Amer. Math. Monthly, 121 (2014), 529-533.
Programs
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Mathematica
Module[{nn=15,b9},b9=Rest[FromDigits[#,9]&/@Tuples[{0,1},nn]];Table[SelectFirst[ b9,Mod[#,n]==0&],{n,100}]] (* Harvey P. Dale, Feb 03 2024 *) -
PARI
a(n,b=9) = if (n, k=1; while(vecmax(digits(k*n, b))>1, k++); k*n); \\ Michel Marcus, Jul 10 2014
Extensions
Data corrected, offset corrected, and b-file replaced by Harvey P. Dale, Feb 03 2024