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A050723 Numbers k such that the decimal expansion of 2^k contains no pair of consecutive equal digits (probably finite). 5
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 21, 22, 28, 29, 30, 31, 32, 34, 35, 36, 37, 48, 54, 55, 56, 66, 67, 68, 69, 80, 87, 104, 126 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
No further terms up to 100000. - T. D. Noe, Sep 18 2012
LINKS
EXAMPLE
2^126 = 85070591730234615865843651857942052864.
MAPLE
q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(2^n)):
select(q, [$0..200])[]; # Alois P. Heinz, Mar 07 2024
MATHEMATICA
Select[Range[0, 10000], !MemberQ[Differences[IntegerDigits[2^#]], 0]&] (* Harvey P. Dale, Dec 24 2011 *)
CROSSREFS
Sequence in context: A032965 A033067 A032512 * A017908 A044965 A044827
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Sep 15 1999
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)