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A137811
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Number of digits in the n-th Woodall prime.
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0
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1, 2, 3, 11, 25, 27, 37, 40, 78, 112, 119, 142, 157, 229, 251, 1603, 2339, 2874, 3731, 4768, 5690, 6920, 6930, 29725, 43058, 45468, 200815
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OFFSET
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1,2
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COMMENTS
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Woodall primes are prime numbers of the form n*2^n-1.
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REFERENCES
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A. Cunningham and H. J. Woodall, Factorisation of Q=(2^q+-q) and (q 2^q+-1), Messenger Math. 47 (1917), pp. 1-38.
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LINKS
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Wilfrid Keller, New Cullen Primes, Mathematics of Computation, Vol. 64, No. 212 (Ocober 1995), pp. 1733-1741.
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FORMULA
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EXAMPLE
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As the sixth Woodall prime is a 27-digit number, we have a(6)= 27
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MATHEMATICA
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IntegerLength/@Select[Table[n 2^n-1, {n, 10000}], PrimeQ] (* The program generates the first 18 terms of the sequence. *) (* Harvey P. Dale, Feb 05 2023 *)
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CROSSREFS
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KEYWORD
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base,hard,nonn
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AUTHOR
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STATUS
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approved
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