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

Author

Clark Kimberling

Keywords

• nonn
• base

Examples

			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
		

Links

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

Crossrefs

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

Programs

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