This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075720 #21 Sep 08 2022 08:45:07 %S A075720 1,3,9,11,14,15,18,23,38,51,66,89,95,140,170,185,186,194,239,258,294, %T A075720 315,345,366,384,386,393,401,404,408,429,459,485,495,506,531,573,611, %U A075720 614,665,675,678,680,683,695,750,771,791,849,870,879,941,954,1016,1086 %N A075720 Numbers n such that n^9 + n + 1 is a prime. %C A075720 For s = 5,8,11,14,17,20,..., n_s=1+n+n^s is always composite for any n>1. Also at n=1, n_s=3 is a prime for any s. So it is interesting to consider only the cases of s != 5,8,11,14,17,20,... and n>1. Here I consider the case s=9 and find several first n's making n_s a prime (or a probable prime). %H A075720 T. D. Noe, <a href="/A075720/b075720.txt">Table of n, a(n) for n = 1..1000</a> %e A075720 9 is a member because at n=9, 1 + n + n^s = 387420499 is a prime. %t A075720 Select[Range[1500], PrimeQ[1 + # + #^9] &] (* _Vincenzo Librandi_, Jul 28 2014 *) %o A075720 (Magma) [n: n in [0..1500] | IsPrime(s) where s is 1+n+n^9]; // _Vincenzo Librandi_, Jul 28 2014 %o A075720 (PARI) for(n=1,10^3,if(isprime(n^9+n+1),print1(n,", "))) \\ _Derek Orr_, Feb 07 2015 %Y A075720 Cf. A002384, A075719, A075722. %K A075720 nonn,easy %O A075720 1,2 %A A075720 _Zak Seidov_, Oct 03 2002