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A137716
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Number of digits in the n-th Cullen prime.
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1
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1, 45, 1423, 1749, 1994, 5573, 9726, 9779, 17964, 27347, 79002, 108761, 145072, 407850
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OFFSET
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1,2
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COMMENTS
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Cullen primes are prime numbers of the form n*2^n+1. This sequence is complete for all values of n up to 3500000.
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REFERENCES
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J. Cullen, Question 15897, Educ. Times, Dec. 1905, 534.
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 Cullen prime is a 5573 digit number, we have a(6)= 5573
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CROSSREFS
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KEYWORD
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hard,nonn,base,changed
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AUTHOR
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STATUS
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approved
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