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Numbers k such that 403*2^k+1 is prime.
1

%I #21 Feb 16 2025 08:33:57

%S 2,4,6,14,16,32,40,74,110,134,252,280,306,356,410,692,760,1220,1286,

%T 1742,2060,2514,3632,7104,7376,10220,10980,18914,20472,20676,22456,

%U 24122,40834,42110,44182,44814,45852,60030,67826,68360,87434,94386,158774,180520

%N Numbers k such that 403*2^k+1 is prime.

%H Jeppe Stig Nielsen, <a href="/A323101/b323101.txt">Table of n, a(n) for n = 1..60</a> (terms n = 1..56 from Robert Price)

%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/riesel1a.html">List of primes k.2^n + 1 for 300 < k < 600</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 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ProthPrime.html">Proth Prime</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>

%p select(k->isprime(403*2^k+1),[$1..1000]); # _Muniru A Asiru_, Jan 04 2019

%t Select[Range[1000], PrimeQ[403*2^# + 1] &]

%K nonn,hard,changed

%O 1,1

%A _Robert Price_, Jan 04 2019