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 A216146 #9 Jan 25 2025 15:02:30
%S A216146 5,83,9377,2470631,97,5,29,13,306503,23173,5,7,7,11,12517,5,13,61,17,
%T A216146 71,5,53,1531477446517,97,101,5,11,1999,53,11,5,67153,7,7,13499,5,13,
%U A216146 28201
%N A216146 Smallest prime factor of 3*(2n+1)^(2n+1) + 2.
%H A216146 Factor DB, <a href="http://factordb.com/index.php?query=3*(2*n%2B1)^(2*n%2B1)%2B2">3*(2*n+1)^(2*n+1)+2</a>.
%e A216146 Indices n = 0,1,2,3 correspond to the 4 primes a(n) = 3*(2n+1)^(2n+1) + 2, and to A160360(2,3,4,5) = 1,3,5,7. The next prime is a(46), with 184 digits too large to be displayed here.
%e A216146 a(22)=1531477446517 is the smaller factor of the semiprime 3*45^45+2.
%t A216146 Table[FactorInteger[3(2n+1)^(2n+1)+2][[1,1]],{n,0,40}] (* _Harvey P. Dale_, Jan 25 2025 *)
%o A216146 (PARI) forstep(n=1,300,2,forprime(p=1,default(primelimit),Mod(n,p)^n*3+2&next;print1(p",");next(2));print1(factor(3*n^n+2)[1,1]","))
%Y A216146 Cf. A160360.
%K A216146 nonn
%O A216146 0,1
%A A216146 _M. F. Hasler_, Sep 02 2012
%E A216146 Comment in example and link added by _M. F. Hasler_, Feb 03 2014