A366583 - OEIS

%I #11 Oct 23 2023 05:22:43

%S 1,1,2,2,7,13,2,2,3,149,2,2,3,5,2,2,103,13,2,2,5,3,2,2,3,3,2,2,23,5,2,

%T 2,3,103,2,2,7,3,2,2,167,11,2,2,5,3,2,2,199,5,2,2,7,163,2,2,29531,5,2,

%U 2,3,5,2,2,3,199,2,2,7,19,2,2,1259,3,2,2,3,3

%N a(2) = a(3) = 1; for n >3, a(n) = smallest prime factor of n-th Tribonacci number.

%H Amiram Eldar, <a href="/A366583/b366583.txt">Table of n, a(n) for n = 2..365</a>

%F a(n) = A020639(A000073(n)).

%e For n=24: A000073(24) = 2*2*2*51343, so a(24)=2.

%t FactorInteger[#][[1, 1]] & /@ LinearRecurrence[{1, 1, 1}, {1, 1, 2}, 78] (* _Amiram Eldar_, Oct 23 2023 *)

%Y Cf. A000073, A231575, A101757.

%K nonn

%O 2,3

%A _Tyler Busby_, Oct 13 2023