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

Author

Patrick De Geest, Sep 15 1999

Keywords

• nonn
• base

Comments

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

Examples

			2^126 = 85070591730234615865843651857942052864.
		

Crossrefs

Cf. A043096, A007377, A046260, A046268.

Programs

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 *)