A043095 Numbers with property that no two consecutive base 9 digits are equal.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79, 82

Offset

1,3

Links

G. C. Greubel, Table of n, a(n) for n = 1..5000

Maple

isA043095 := proc(n)
    dgs := convert(n, base, 9) ;
    for i from 2 to nops(dgs) do
        if op(i, dgs) = op(i-1, dgs) then
            return false;
        end if;
    end do:
    true ;
end proc:
A043095 := proc(n)
    option remember;
    if n =1 then
        0;
    else
        for a from procname(n-1)+1 do
            if isA043095(a) then
                return a;
            end if;
        end do;
    end if;
end proc:
seq(A043095(n), n=1..120) ; # R. J. Mathar, Dec 28 2023

Mathematica

Select[Range[0, 100], !MemberQ[Flatten[Differences/@Partition[ IntegerDigits[ #, 9], 2, 1]], 0]&] (* Harvey P. Dale, Apr 05 2014 *)

Prog

(PARI) isok(n) = {my(d = digits(n, 9)); for (i=2, #d, if (d[i] == d[i-1], return (0)); ); return (1); } \\ Michel Marcus, Oct 11 2017

Crossrefs

Cf. A000975 (base-2 analog), A031941 or A043089 (base-3 analog), A031942 or A043090 (base-4 analog), A031943 or A043091 (base-5 analog), A043092, ..., A043096 (base-6 through base-10 analog).

Sequence in context: A209931 A052382 A367733 * A055572 A052040 A328781

Adjacent sequences: A043092 A043093 A043094 * A043096 A043097 A043098

Keyword

nonn,base

Author

Clark Kimberling

Status

approved