A044820 - OEIS

%I #16 Jan 04 2021 18:19:13

%S 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,

%T 98,101,111,121,131,141,151,161,162,172,180,181,182,183,184,185,186,

%U 187,188,192,202,212,222,232,242,243,253,263,270,271,272,273,274,275,276

%N Positive integers having distinct base-9 run lengths.

%H David A. Corneth, <a href="/A044820/b044820.txt">Table of n, a(n) for n = 1..10000</a>

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

%p rlset := proc(L::list)

%p     local lset,rl,i ;

%p     lset := [] ;

%p     rl := 1 ;

%p     for i from 2 to nops(L) do

%p         if op(i,L) = op(i-1,L) then

%p             rl := rl+1 ;

%p         else

%p             lset := [op(lset),rl] ;

%p             rl := 1;

%p         end if;

%p     end do:

%p     lset := [op(lset),rl] ;

%p end proc:

%p isA044820 := proc(n)

%p     local dgs,rl;

%p     dgs := convert(n,base,9) ;

%p     rl := rlset(dgs) ;

%p     if nops(rl) = nops( convert(rl,set)) then

%p         true;

%p     else

%p         false;

%p     end if;

%p end proc:

%p for n from 1 to 400 do

%p     if isA044820(n) then

%p         printf("%d,",n) ;

%p     end if;

%p end do: # _R. J. Mathar_, Jan 18 2018

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

%K nonn,base

%O 1,2

%A _Clark Kimberling_