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 A002261 M2425 N0960 #45 Dec 22 2024 09:29:16 %S A002261 1,3,5,7,19,21,43,81,125,127,209,211,3225,4543,10179,15329,18759, %T A002261 28277,93279,105741,268009,412447,525589,644677,886071,960901,1343347, %U A002261 2230369,2476839,2691961,2897409,3771821,8103463 %N A002261 Numbers k such that 11*2^k + 1 is prime. %D A002261 H. Riesel, "Prime numbers and computer methods for factorization", Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384. %D A002261 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A002261 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A002261 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>. %H A002261 Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1.html">List of primes k.2^n + 1 for k < 300</a>. %H A002261 Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>. %H A002261 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>. %H A002261 R. M. Robinson, <a href="https://doi.org/10.1090/S0002-9939-1958-0096614-7">A report on primes of the form k.2^n+1 and on factors of Fermat numbers</a>, Proc. Amer. Math. Soc., 9 (1958), 673-681. %H A002261 <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a> %t A002261 Select[Range[1000], PrimeQ[11*2^#+1] &] (* _Amiram Eldar_, Dec 12 2018 *) %o A002261 (PARI) is(n)=ispseudoprime(11*2^n+1) \\ _Charles R Greathouse IV_, Feb 20 2017 %K A002261 hard,nonn %O A002261 1,2 %A A002261 _N. J. A. Sloane_ %E A002261 Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013 %E A002261 a(30)-a(32) from http://www.prothsearch.com/riesel1.html by _Robert Price_, Dec 12 2018 %E A002261 a(33) from _Jeppe Stig Nielsen_, Dec 22 2024