A061947 - OEIS

%I #17 Dec 05 2020 06:35:50

%S 1,2,3,6,9,17,47,61,69,137,323,385,674,731,884,1245,1253,17204,35580,

%T 37282,73270,74919,78625,98413,119017,263197,313732,402321,467738,

%U 661300,4757138,8445220,9481937

%N Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 18 (most significant digit on right).

%C This sequence differs from A029511 in that all least significant zeros are removed before concatenation.

%C No more terms < 10^7. - _Lars Blomberg_, Oct 23 2011

%H <a href="/index/N#concat">Index entries for related sequences</a>

%e See A061931 for example.

%t b = 18; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[c, IntegerDigits[IntegerReverse[#, b], b]], b], #] &] (* _Robert Price_, Mar 08 2020 *)

%o (PARI) lista(nn) = my(s, t); for(k=1, nn, s=k/18^valuation(k, 18); while(s, t=t*18+s%18; s\=18); if(t%k==0, print1(k, ", "))); \\ _Jinyuan Wang_, Dec 05 2020

%Y Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.

%K nonn,base,more

%O 1,2

%A Larry Reeves (larryr(AT)acm.org), May 24 2001

%E Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002

%E a(29)-a(33) from _Lars Blomberg_, Oct 23 2011