A043089 Every string of 2 consecutive base-3 digits contains exactly 2 distinct numbers.

0, 1, 2, 3, 5, 6, 7, 10, 11, 15, 16, 19, 20, 21, 23, 30, 32, 33, 34, 46, 47, 48, 50, 57, 59, 60, 61, 64, 65, 69, 70, 91, 92, 96, 97, 100, 101, 102, 104, 138, 140, 141, 142, 145, 146, 150, 151, 172, 173, 177, 178, 181, 182, 183, 185, 192

Offset

0,3

Comments

Essentially the same as A031941. - R. J. Mathar, Oct 20 2008

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Mathematica

Select[Range[0, 200], FreeQ[Differences[IntegerDigits[#, 3]], 0]&] (* Harvey P. Dale, Feb 25 2022 *)

Prog

(PARI) a(n, base=3) = { for (b=0, oo, if (n <= (base-1)*2^b, my (v=ceil(n/2^b), p=(n-1)%(2^b)); while (b>0, v=base*v+vecsort([(v-1)%base, (v+1)%base])[1+bittest(p, b--)]; ); return (v), n -= (base-1)*2^b); ); } \\ Rémy Sigrist, Sep 15 2022

Crossrefs

Cf. A031941.

Sequence in context: A240101 A032892 A031941 * A088952 A303541 A293523

Adjacent sequences: A043086 A043087 A043088 * A043090 A043091 A043092

Keyword

nonn,base

Author

Clark Kimberling

Status

approved