A330833 - OEIS

%I #8 Jan 11 2020 21:40:15

%S 2,2,3,2,5,2,3,17,2,7,41,5,59,2,71,13,89,101,2,17,131,3,167,173,23,29,

%T 293,383,5,13,43,677,701,743,17,761,773,827,839,857,911,1091,1097,5,

%U 1163,1181,1193,1217,73,1373,1427,79,1487,1559,1583,83,2,1709,1811,1847,1931,1973,2129,2273,2309,2339,2411,2663,2729,2789,2957

%N a(n) = first prime factor p of the term A330832(n) = p*q.

%H Walter Kehowski, <a href="/A330833/b330833.txt">Table of n, a(n) for n = 1..4731</a>

%e a(5) = 5 and, since A330834(5) = 3, then A330835(5) = (5^3-1)/(5-1) = 31 is prime.

%Y Cf. A003424, A023194, A023195, A085104, A330832, A330834, A330835.

%K nonn,easy

%O 1,1

%A _Walter Kehowski_, Jan 08 2020