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 A119909 Numbers n such that n and n^2 written in base 3 are zero-free. 0
 1, 2, 4, 5, 7, 22, 43, 131, 394 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS No more terms < 3^20. - Joshua Zucker, Jun 05 2006 LINKS EXAMPLE n: 1, 2, 4, 5, 7, 22, 43, 131, 394 n^2: 1, 4, 16, 25, 49, 484, 1849, 17161, 155236 n written in base 3: 1, 2, 11, 12, 21, 211, 1121, 11212, 112121 n^2 written in base 3: 1,11,121,221,1211,122221,2112111,212112121,21212221111 MATHEMATICA Select[Range[500], DigitCount[#, 3, 0]==DigitCount[#^2, 3, 0]==0&] (* Harvey P. Dale, Feb 06 2015 *) PROG (PARI) isok(n) = vecmin(digits(n, 3)) && vecmin(digits(n^2, 3)); \\ Michel Marcus, Oct 10 2013 CROSSREFS Subsequence of A032924. Sequence in context: A005620 A049915 A244332 * A301521 A097698 A233524 Adjacent sequences:  A119906 A119907 A119908 * A119910 A119911 A119912 KEYWORD base,more,nonn AUTHOR Zak Seidov, May 28 2006 STATUS approved

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Last modified October 16 06:10 EDT 2019. Contains 328046 sequences. (Running on oeis4.)