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A137716 Number of digits in the n-th Cullen prime. 1
1, 45, 1423, 1749, 1994, 5573, 9726, 9779, 17964, 27347, 79002, 108761, 145072, 407850 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Cullen primes are prime numbers of the form n*2^n+1. This sequence is complete for all values of n up to 3500000.
REFERENCES
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.
LINKS
Cullen Primes, Definition and Status.
Wilfrid Keller, New Cullen Primes, Mathematics of Computation, Vol. 64, No. 212 (Ocober 1995), pp. 1733-1741.
FORMULA
a(n) = A055642(A050920(n)). [Corrected by Georg Fischer, Nov 18 2023]
EXAMPLE
As the sixth Cullen prime is a 5573 digit number, we have a(6)= 5573
CROSSREFS
Sequence in context: A145151 A027476 A062262 * A035521 A107399 A053112
KEYWORD
hard,nonn,base,changed
AUTHOR
Ant King, Feb 09 2008
STATUS
approved

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)