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A043089
Every string of 2 consecutive base-3 digits contains exactly 2 distinct numbers.
9
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
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
KEYWORD
nonn,base
STATUS
approved