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A050724
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Numbers k such that the decimal expansion of 3^k contains no pair of consecutive equal digits (probably finite).
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3
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 21, 22, 24, 26, 42, 66, 67, 133
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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3^133 = 2865014852390475710679572105323242035759805416923029389510561523.
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MAPLE
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q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(3^n)):
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MATHEMATICA
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Select[Range[0, 500], !MemberQ[Differences[IntegerDigits[3^#]], 0]&] (* Harvey P. Dale, Nov 15 2011 *)
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PROG
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(PARI) isok(n) = {my(d = digits(3^n), c = d[1]); for (i=2, #d, if (d[i] == c, return (0)); c = d[i]; ); return (1); } \\ Michel Marcus, Oct 16 2019
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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