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 A006552 M1848 #33 Sep 08 2022 08:44:35 %S A006552 2,8,32,54,114,414,1400,1850,2848,4874,7268,19290,337590,1183414 %N A006552 Numbers k such that k*3^k + 1 is prime. %D A006552 H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191. %D A006552 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006552 H. Dubner, <a href="/A005849/a005849.pdf">Generalized Cullen numbers</a>, J. Rec. Math., 21 (No. 3, 1989), 190-191. (Annotated scanned copy) %H A006552 G. Loeh, <a href="http://guenter.loeh.name/gc/status.html">Generalized Cullen primes</a> %t A006552 Select[Range[10000], PrimeQ[# 3^# + 1] &] (* _Vincenzo Librandi_, Dec 02 2015 *) %o A006552 (Magma) [n: n in [0..420] | IsPrime(n*3^n+1)]; // _Vincenzo Librandi_, Dec 02 2015 %o A006552 (PARI) is(n)=ispseudoprime(n*3^n+1) \\ _Charles R Greathouse IV_, Feb 17 2017 %K A006552 nonn,hard %O A006552 1,1 %A A006552 _N. J. A. Sloane_ %E A006552 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008 %E A006552 a(14) from Loeh link by _Ray Chandler_, Apr 10 2016