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A050724 Numbers k such that the decimal expansion of 3^k contains no pair of consecutive equal digits (probably finite). 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
No additional terms up to 50000. - Harvey P. Dale, Nov 15 2011
No additional terms up to 100000. - Michel Marcus, Oct 16 2019
LINKS
EXAMPLE
3^133 = 2865014852390475710679572105323242035759805416923029389510561523.
MAPLE
q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(3^n)):
select(q, [$0..200])[]; # Alois P. Heinz, Mar 07 2024
MATHEMATICA
Select[Range[0, 500], !MemberQ[Differences[IntegerDigits[3^#]], 0]&] (* Harvey P. Dale, Nov 15 2011 *)
PROG
(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
CROSSREFS
Sequence in context: A023779 A367611 A247812 * A336813 A209860 A287513
KEYWORD
nonn,base,more
AUTHOR
Patrick De Geest, Sep 15 1999
STATUS
approved

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Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)