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 A007646 M2699 #17 Apr 08 2019 03:07:11 %S A007646 1,3,7,33,67,223,663,912,1383,3777,3972,10669,48375 %N A007646 Numbers k such that k*4^k + 1 is prime. %D A007646 H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191. %D A007646 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A007646 G. Loeh, <a href="http://guenter.loeh.name/gc/status.html">Generalized Cullen primes</a> %o A007646 (PARI) is(n)=ispseudoprime(n*4^n+1) \\ _Charles R Greathouse IV_, Feb 17 2017 %K A007646 hard,nonn %O A007646 1,2 %A A007646 _N. J. A. Sloane_ %E A007646 More terms from _Robert G. Wilson v_ %E A007646 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008