A137811 Number of digits in the n-th Woodall prime.
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, 359799, 382007, 441847, 606279, 712818, 1129757, 5122515
Offset: 1
Examples
As the sixth Woodall prime is a 27-digit number, we have a(6)= 27
Links
- Allan Cunningham and H. J. Woodall, Factorisation of Q=(2^q+-q) and (q 2^q+-1), Messenger Math., Vol. 47 (1917), pp. 1-38.
- Wilfrid Keller, New Cullen Primes, Mathematics of Computation, Vol. 64, No. 212 (Ocober 1995), pp. 1733-1741.
- Woodhall Primes, Definition And Status.
Programs
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Mathematica
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 *)
Extensions
a(28)-a(34) from Amiram Eldar, Jul 19 2025
Comments