A124063 - OEIS

%I #10 Mar 14 2015 18:27:58

%S 1,1,1,2,3,3,6,11,3,9,12,20,5,3,12,35,8,5,8,13,3,15,28,5,13,16,21,18,

%T 35,53,3,18,56,49,3,21,45,63,75,54,77,14,5,18,77,91,29,3,24,75,137,3,

%U 27,39,56,119,3,30,76,5,23,3,33,47,3,36,134,5,28,47,50,35,103,3,39,107,3,42

%N a(1)=a(2)=1. a(n) = the sum of the terms, from among the first (n-2) terms of the sequence, which divide a(n-1).

%C First occurrence of k or 0 if not present: 1,4,5,0,13,7,0,17,10,0,8,11,20,42,22,26,0,28,220,12. - _Robert G. Wilson v_, Nov 04 2006

%e a(11)= 12. Among the first 10 terms of the sequence a(1)=1, a(2)=1, a(3)=1, a(4)=2, a(5)=3, a(6)=3, a(7)=6 and a(9)=3 each divide 12. So a(12) = 1+1+1+2+3+3+6+3 = 20.

%t f[ s_ ] := Append[ s, Plus @@ Select[ Most@s, Mod[ s[ [ -1 ] ], # ] == 0 & ] ];; Nest[ f, {1, 1}, 76 ] (* _Robert G. Wilson v_ *)

%K nonn

%O 1,4

%A _Leroy Quet_, Nov 04 2006

%E More terms from _Robert G. Wilson v_, Nov 04 2006