|
%I #46 Oct 09 2019 13:05:05
%S 1,2,3,5,8,4,12,6,18,9,27,36,63,7,70,10,80,16,96,24,120,15,135,45,180,
%T 20,200,25,225,75,300,30,330,11,341,31,372,62,434,14,448,28,476,17,
%U 493,29,522,58,580,116,696,87,783,261,1044,174,1218,21,1239,59,1298,22,1320,33,1353
%N a(1) = 1, a(2) = 2; thereafter a(n+1) = smallest unused divisor of a(n) if there are any, otherwise a(n) + a(n-1).
%H Ivan Neretin, <a href="/A323890/b323890.txt">Table of n, a(n) for n = 1..10000</a>
%e a(6) = 4, and all divisors of 4 are already used, hence a(7) = a(6) + a(5) = 8 + 4 = 12. Now the smallest unused divisor of 12 is 6, hence a(8) = 6.
%t Nest[Append[#, If[(d = Complement[Divisors@#[[-1]], #]) == {}, #[[-1]] + #[[-2]], Min[d]]] &, {1, 2}, 63]
%Y Cf. A050196, A085947.
%K nonn,look
%O 1,2
%A _Ivan Neretin_, Sep 02 2019
|
