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%I #8 Jan 17 2019 10:08:17
%S 1,2,4,7,8,11,22,32,50,55,80,106,155,172,208,235,391,436,470,776,1558,
%T 1675,2795,2908,2947,3970,4004,5774,6248,11278,11824,17824,41708,
%U 51530,92500,137930,192122,242488,251947,414355
%N Numbers n such that 9*2^(2*n-1) - 1 is prime.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ThabitibnKurrahRule.html">Thabit ibn Kurrah's rules</a>
%H Kosmaj, <a href="http://www.15k.org/riesellist.html">Riesel list k<300</a>.
%e 9*2^(2*1-1) - 1 = 17 so a(1)=1
%e 9*2^(2*2-1) - 1 = 71 so a(2)=2
%e 9*2^(2*3-1) - 1 = 287 is not prime
%e 9*2^(2*4-1) - 1 = 1151 is prime so a(3)=4
%o (PARI) for (i=1,500,if(isprime(9*2^(2*i-1)-1),print1(i,",")))
%K nonn
%O 1,2
%A Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 17 2004
%E 8 additional terms, corresponding to probable primes, from _Ryan Propper_, Jun 18 2005
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
%E Edited by _T. D. Noe_, Oct 30 2008
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