A127990 - OEIS

%I #11 Mar 13 2020 12:43:01

%S 3,7,19,43,83,13,227,113,23,17,883,37,1459,1823,2243,389,11,431,13,

%T 5323,6163,373,89,9203,103,83,257,443,439,367,19843,73,647,26183,9521,

%U 797,1607,36559,3593,42643,2417,49367,1709,53,173,7207,1609,73699,163,7573

%N Largest prime factor of 2*n^3 - 2*n + 9.

%C All numbers generated by the irreducible polynomial 2*n^3 - 2*n + 9 (A127989) are odd and composite. Smallest prime factor A127991, number of prime factors A127992

%H Amiram Eldar, <a href="/A127990/b127990.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A006530(A127989(n)). - _Amiram Eldar_, Mar 13 2020

%t a = {}; Do[AppendTo[a, 2n^3 - 2n + 9], {n, 1, 300}]; b = {}; Do[c = FactorInteger[a[[n]]]; d = c[[Length[c]]]; AppendTo[b, d[[1]]], {n, 1, Length[a]}]; b

%Y Cf. A006530, A127989, A127991, A127992.

%K nonn

%O 1,1

%A _Artur Jasinski_, Feb 10 2007