A044818 Positive integers having distinct base-7 run lengths.

1, 2, 3, 4, 5, 6, 8, 16, 24, 32, 40, 48, 49, 56, 57, 58, 59, 60, 61, 62, 65, 73, 81, 89, 97, 98, 106, 112, 113, 114, 115, 116, 117, 118, 122, 130, 138, 146, 147, 155, 163, 168, 169, 170, 171, 172, 173, 174, 179, 187, 195, 196, 204, 212, 220, 224, 225, 226, 227, 228

Offset

1,2

Links

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

Example

40=55_7 has a single run length of 2 and is in the sequence. 211=421_7 has three runs of length 1 as is not in the sequence. - R. J. Mathar, Jan 18 2018

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:
isA044818 := proc(n)
    local dgs, rl;
    dgs := convert(n, base, 7) ;
    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 isA044818(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: A039089 A044956 A297139 * A048304 A043710 A296703

Adjacent sequences: A044815 A044816 A044817 * A044819 A044820 A044821

Keyword

nonn,base

Author

Clark Kimberling

Status

approved