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 A109273 #12 Aug 24 2021 01:45:06 %S A109273 1,4,10,16,22,28,40,52,58,70,88,100,112,130,136,148,196,232,238,250, %T A109273 256,280,310,316,352,382,400,418,430,442,478,490,556,562,592,598,616, %U A109273 640,682,742,772,796,808,820,862,880,928,970,976,1030,1048,1060,1096,1102 %N A109273 Numbers k such that k+1 is the smallest prime factor of k^3 + 3^k. %C A109273 Except for the first term, 2k+1 is composite. %o A109273 (PARI) isok(n) = factor(n^3+3^n)[1, 1] == (n+1); \\ _Michel Marcus_, Oct 06 2013 %Y A109273 Cf. A001585. %K A109273 nonn %O A109273 1,2 %A A109273 _Zak Seidov_ and _Max Alekseyev_, Jun 25 2005