A044820 Positive integers having distinct base-9 run lengths.

1, 2, 3, 4, 5, 6, 7, 8, 10, 20, 30, 40, 50, 60, 70, 80, 81, 90, 91, 92, 93, 94, 95, 96, 97, 98, 101, 111, 121, 131, 141, 151, 161, 162, 172, 180, 181, 182, 183, 184, 185, 186, 187, 188, 192, 202, 212, 222, 232, 242, 243, 253, 263, 270, 271, 272, 273, 274, 275, 276

Offset

1,2

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Example

242 = 288_9 is in the sequence as it has distinct run lengths of distinct digits (1, 2). - David A. Corneth, Jan 04 2021

Maple

rlset := proc(L::list)
    local lset, rl, i ;
    lset := [] ;
    rl := 1 ;
    for i from 2 to nops(L) do
        if op(i, L) = op(i-1, L) then
            rl := rl+1 ;
        else
            lset := [op(lset), rl] ;
            rl := 1;
        end if;
    end do:
    lset := [op(lset), rl] ;
end proc:
isA044820 := proc(n)
    local dgs, rl;
    dgs := convert(n, base, 9) ;
    rl := rlset(dgs) ;
    if nops(rl) = nops( convert(rl, set)) then
        true;
    else
        false;
    end if;
end proc:
for n from 1 to 400 do
    if isA044820(n) then
        printf("%d, ", n) ;
    end if;
end do: # R. J. Mathar, Jan 18 2018

Crossrefs

Cf. A044813, A044814, A044815, A044816, A044817, A044818, A044819, A044820, A044821, A044822, A044823, A044824, A044825, A044826, A044827 (base 2 to base 16).

Sequence in context: A039172 A044958 A297145 * A048306 A043712 A296709

Adjacent sequences: A044817 A044818 A044819 * A044821 A044822 A044823

Keyword

nonn,base

Author

Clark Kimberling

Status

approved