A147829 - OEIS

%I #13 Mar 21 2016 03:13:43

%S 0,9,99,333,7497,99999,333333,2842857,49999986,111111111,9999999999,

%T 99909090909,249999999999,2299923076923,21427857142857,

%U 333333333333333,2499999999999993,11764705294117647,111111111111111111,1526315788947368421

%N Minimum number k for which the digital sum of k*n is 9*n.

%p P:=proc(i) local j,k,n,ok,w; for n from 0 by 1 to i do j:=-1; ok:=1; while ok=1 do j:=j+1; w:=0; k:=n*j; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; if w=9*n then ok:=0; print(j); fi; od; od; end: P(100);

%o (PARI) a(n) = {my(k = 0); while (sumdigits(k*n) != 9*n, k++); k;}; \\ _Michel Marcus_, Mar 21 2016

%Y Cf. A147822-A147828, A147830, A147831.

%K easy,nonn,base

%O 0,2

%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Nov 14 2008

%E Edited by _Charles R Greathouse IV_, Nov 01 2009

%E a(7)-a(12) from _Donovan Johnson_, Sep 16 2012

%E a(13)-a(19) from _Chai Wah Wu_, Mar 20 2016