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 A105122 #21 Jul 23 2024 02:58:37 %S A105122 2,6,12,232,262,280,330,430,508,772,786,852,1012,1522,1566,1626,1810, %T A105122 2346,2556,2676,3658,3888,3910,4018,4048,4258,4830,5188,5322,5478, %U A105122 5848,6090,6366,6568,7018,7458,7602,7606,7822,8178,8928,9420,9618,9676,10398 %N A105122 Positive integers n such that n^11 + 1 is semiprime. %C A105122 Since n^11 + 1 = (n+1) * (n^10 - n^9 + n^8 - n^7 + n^6 - n^5 + n^4 - n^3 + n^2 - n + 1), n^11 + 1 can be prime only if both (n+1) and (n^10 - n^9 + n^8 - n^7 + n^6 - n^5 + n^4 - n^3 + n^2 - n + 1) are prime. %H A105122 Robert Price, <a href="/A105122/b105122.txt">Table of n, a(n) for n = 1..4303</a> %e A105122 2^11+1 = 2049 = 3 * 683, %e A105122 6^11+1 = 362797057 = 7 * 51828151, %e A105122 1012^11+1 = 1140212079231804336089593374834689 = 1013 * 1125579545144920371263172137053. %t A105122 Select[ Range[10721], PrimeQ[ # + 1] && PrimeQ[(#^11 + 1)/(# + 1)] &] (* _Robert G. Wilson v_, Apr 09 2005 *) %Y A105122 Cf. A001358 (semiprimes), A085722, A096173, A186669, A104238, A103854, A105041, A105066, A105078, A105122, A105142, A105237, A104335, A104479, A104494, A104657, A105282. %K A105122 easy,nonn %O A105122 1,1 %A A105122 _Jonathan Vos Post_, Apr 08 2005 %E A105122 More terms from _Robert G. Wilson v_, Apr 09 2005