A050723 Numbers k such that the decimal expansion of 2^k contains no pair of consecutive equal digits (probably finite).

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

Offset

1,3

Comments

No further terms up to 100000. - T. D. Noe, Sep 18 2012

Links

Table of n, a(n) for n=1..41.

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

Cf. A043096, A007377, A046260, A046268.

Sequence in context: A032965 A033067 A032512 * A017908 A044965 A044827

Adjacent sequences: A050720 A050721 A050722 * A050724 A050725 A050726

Keyword

nonn,base

Author

Patrick De Geest, Sep 15 1999

Status

approved