A Woodall number is a number of the form

The first few are 1, 7, 23, 63, 159, 383, ... (Sloane's A003261).

The first few for which the Woodall number is prime are given by 2, 3, 6, 30, 75, 81, 115, 123, 249, 362, 384, 462, 512, 751, 822, 5312, 7755, 9531, 12379, 15822, 18885, 22971, 23005, 98726, 143018, 151023, 667071, 1195203, ... (Sloane's A002234), corresponding to s of 7, 23, 383, 32212254719, 2833419889721787128217599, ... (Sloane's A050918). The largest known Woodall prime has index 1467763 (http://primes.utm.edu/primes/page.php?id=80955), 441847 decimal digits, and was found in Jun. 2007.

Caldwell, C. K. "The Top Twenty: Woodall Primes." http://www.utm.edu/research/primes/lists/top20/Woodall.html.

Guy, R. K. "Cullen Numbers." §B20 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, p. 77, 1994.

Leyland, P. http://research.microsoft.com/~pleyland/factorization/cullen_woodall/2-.txt.

Ribenboim, P. The New Book of Prime Number Records. New York: Springer-Verlag, pp. 360-361, 1996.

Rodenkirch, M. and Ballinger, R. "Woodall Primes: Definition and Status." http://www.prothsearch.net/woodall.html.

Sloane, N. J. A. Sequences A002234/M0820, A003261/M4379, and A050918 in "The On-Line Encyclopedia of Integer Sequences."

CITE THIS AS:

Weisstein, Eric W. "Woodall Number." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/WoodallNumber.html