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A001772 Numbers n such that 11*2^n - 1 is prime.
(Formerly M2145 N0854)
3

%I M2145 N0854

%S 2,26,50,54,126,134,246,354,362,950,1310,2498,6926,11826,31734,67850,

%T 74726,96150,374114,696438,743322,1044086,1104606,1261478

%N Numbers n such that 11*2^n - 1 is prime.

%D H. Riesel, ``Prime numbers and computer methods for factorization,'' Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%D H. C. Williams and C. R. Zarnke, Math. Comp., 22 (1968), 420-422.

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

%H Kosmaj, <a href="http://www.15k.org/riesellist.html">Riesel list k<300</a>.

%o (PARI) is(n)=ispseudoprime(11*2^n-1) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A050525.

%Y Cf. A002261, 11*2^n+1 is prime.

%K hard,nonn,nice

%O 1,1

%A _N. J. A. Sloane_.

%E More terms from _Hugo Pfoertner_, Jun 23 2004

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

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Last modified November 13 10:29 EST 2019. Contains 329093 sequences. (Running on oeis4.)