A050723 - OEIS

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 (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	`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`