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A001770 Numbers n such that 5*2^n - 1 is prime.
(Formerly M1087 N0415)
+0
4
2, 4, 8, 10, 12, 14, 18, 32, 48, 54, 72, 148, 184, 248, 270, 274, 420, 1340, 1438, 1522, 1638, 1754, 1884, 2014, 2170, 2548, 2622, 2652, 2704, 13510, 21738, 25624, 41934, 51478, 52540, 53230, 172300, 245728, 350028 (list; graph; listen)
OFFSET

1,1

REFERENCES

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

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

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

LINKS

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

CROSSREFS

Cf. A050522.

Cf. A002254, 5*2^n+1 is prime.

Sequence in context: A039011 A132190 A155037 this_sequence A032494 A125953 A047464

Adjacent sequences: A001767 A001768 A001769 this_sequence A001771 A001772 A001773

KEYWORD

nonn,nice,hard

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

More terms from Hugo Pfoertner (hugo(AT)pfoertner.org), Jun 23 2004

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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