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A263307
Numbers without consecutive repeated digits in base 2 and in base 3.
0
1, 2, 5, 10, 21, 1365, 2730
OFFSET
1,2
COMMENTS
Intersection of A000975 and A031941. - Michel Marcus, Oct 14 2015
It seems likely that there are no further terms.
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: A361779 A360748 A151497 * A278441 A323939 A110744
KEYWORD
nonn,base
AUTHOR
Robin Powell, Oct 13 2015
STATUS
approved