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A050725 Decimal expansion of 4^n contains no pair of consecutive equal digits (probably finite). 1
0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 14, 15, 16, 17, 18, 24, 27, 28, 33, 34, 40, 52, 63 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

No additional terms up to 1200. - Harvey P. Dale, Mar 30 2011

No additional terms up to 100000. - Michel Marcus, Oct 16 2019

Half of even terms of A050723. - Joerg Arndt, Oct 16 2019

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

4^63 = 85070591730234615865843651857942052864.

MATHEMATICA

Select[Range[0, 70], FreeQ[Differences[IntegerDigits[4^#]], 0]&] (* Harvey P. Dale, Jul 25 2013 *)

PROG

(PARI) isok(n) = {my(d = digits(4^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

Cf. A000302, A030701, A046262, A046270.

Sequence in context: A191927 A116000 A251595 * A080571 A165805 A319975

Adjacent sequences:  A050722 A050723 A050724 * A050726 A050727 A050728

KEYWORD

nonn,base,more

AUTHOR

Patrick De Geest, Sep 15 1999

STATUS

approved

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Last modified May 26 13:59 EDT 2022. Contains 354092 sequences. (Running on oeis4.)