%I #41 Sep 19 2019 03:27:41

%S 1,6,13,18,21,22,25,28,66,93,118,289,412,453,525,726,828,1420,1630,

%T 3076,3118,4452,4941,5236,6346,9133,13401,14214,18766,37249,42685,

%U 47805,61372,74178,600270,922782,1130884,2345001,3176269,3570132,3649810

%N Numbers k such that 33*2^k+1 is prime.

%C With a(37) = 1130884 the list is complete up to 2.1*10^6, but k = 2345001, 3176269 and 3570132 are also in the sequence, cf. Ballinger & Keller link. - _M. F. Hasler_, Jul 20 2019

%C The mentioned limit up to which the list is complete, has reached about 3.7*10^6 (PrimeGrid). - _Jeppe Stig Nielsen_, Sep 19 2019

%H Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>

%H Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1.html">List of primes k.2^n + 1 for k < 300</a>. (Created April 1998, updated July 2019.)

%H Chris K. Caldwell, <a href="https://primes.utm.edu/primes/page.php?id=129931">The Prime Database: 33*2^3649810+1</a>.

%H Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>

%H M. B. Porter et al, <a href="/wiki/Factors_of_33*2%5En%2B1">Factors of 33*2^n+1</a>, OEIS wiki, updated July 2019

%H PrimeGrid, <a href="https://www.primegrid.com/stats_div_llr.php">Fermat Divisor Search range statistics</a>.

%H <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>

%o (PARI) is(n)=ispseudoprime(33*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A002240 (33*2^n-1 is prime).

%K nonn,hard

%O 1,2

%A _James R. Buddenhagen_

%E Added more terms from the Ballinger & Keller page. - _Joerg Arndt_, Apr 07 2013

%E Added & edited links & cross-references. - _M. F. Hasler_, Jul 20 2019

%E a(38)-a(41) from _Jeppe Stig Nielsen_, Sep 18 2019