login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A263307 Numbers without consecutive repeated digits in base 2 and in base 3. 0
1, 2, 5, 10, 21, 1365, 2730 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Intersection of A000975 and A031941. - Michel Marcus, Oct 14 2015

It seems likely that there are no further terms.

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

10 is 1010 in base 2 and 101 in base 3; no two of the same digit are next to one another and so 10 is a term.

Similarly 21 is 10101 in base 2 and 210 in base 3 so it is also a term.

PROG

(PARI) isokd(d) = {dd = vector(#d-1, k, abs(d[k+1]-d[k])); if (#dd, vecmin(dd), 1); }

isok(n) = isokd(binary(n)) && isokd(digits(n, 3)); \\ Michel Marcus, Oct 14 2015

CROSSREFS

Cf. A000975 (base 2), A031941 (base 3).

Sequence in context: A327764 A192317 A151497 * A278441 A323939 A110744

Adjacent sequences:  A263304 A263305 A263306 * A263308 A263309 A263310

KEYWORD

nonn,base

AUTHOR

Robin Powell, Oct 13 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 18 00:59 EDT 2022. Contains 353779 sequences. (Running on oeis4.)