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A050918
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Woodall primes: primes of form k*2^k-1.
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15
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7, 23, 383, 32212254719, 2833419889721787128217599, 195845982777569926302400511, 4776913109852041418248056622882488319, 1307960347852357218937346147315859062783, 225251798594466661409915431774713195745814267044878909733007331390393510002687
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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M. F. Hasler, Table of n, a(n) for n = 1..15 (all terms < 10^999).
Ray Ballinger, Woodall Primes: Definition and Status
C. K. Caldwell, Woodall Numbers
Brady Haran and Matt Parker, 383 is cool, Numberphile video, 2017.
Eric Weisstein's World of Mathematics, Woodall Number
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FORMULA
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a(n) = A002234(n)*2^A002234(n) - 1. - M. F. Hasler, May 10 2017
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MATHEMATICA
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Select[Table[n 2^n - 1, {n, 300}], PrimeQ] (* Harvey P. Dale, Jul 12 2012 *)
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PROG
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(PARI) for(n=2, 999, ispseudoprime(p=n*2^n-1)&&print1(p", ")) \\ M. F. Hasler, May 10 2017
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CROSSREFS
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Cf. A002234, A003261.
Sequence in context: A187487 A299643 A034192 * A322557 A228699 A159485
Adjacent sequences: A050915 A050916 A050917 * A050919 A050920 A050921
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane, Dec 30 1999
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STATUS
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approved
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