cp's OEIS Frontend

A100800 Let f(n) = n + sum of the digits of n. If f(n) is multiple of n then a(n)= f(n) else a(n) = f(f(f(n)))... until one gets a multiple of n; a(n) = 0 if no such number exists.

%I A100800 #4 Dec 05 2013 19:57:00
%S A100800 2,4,6,8,10,12,14,16,18,130,341,24,130,392,30,320,119,36,950,80,84,88,
%T A100800 115,96,950,104,54,392,406,120,341,736,231,578,455,72,851,950,507,320,
%U A100800 328,210,559,440,90,184,658,480,392,950,204,416,530,162,1430,2128,114
%N A100800 Let f(n) = n + sum of the digits of n. If f(n) is multiple of n then a(n)= f(n) else a(n) = f(f(f(n)))... until one gets a multiple of n; a(n) = 0 if no such number exists.
%C A100800 Conjecture: No term is zero.
%e A100800 a(10) = 130, f(10) = 10 + 1 = 11, f(f(10)) = f(11) = 13,... we get the sequence 10,11,13,17,25,32,37,47,58,71,79,95,109,119,130,...
%Y A100800 Cf. A100801, A101183.
%K A100800 base,easy,nonn
%O A100800 1,1
%A A100800 _Amarnath Murthy_, Dec 17 2004
%E A100800 Extended by _Ray Chandler_, Dec 19 2004