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A050918 Woodall primes: primes of form k*2^k-1. 16
7, 23, 383, 32212254719, 2833419889721787128217599, 195845982777569926302400511, 4776913109852041418248056622882488319, 1307960347852357218937346147315859062783, 225251798594466661409915431774713195745814267044878909733007331390393510002687 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
M. F. Hasler, Table of n, a(n) for n = 1..15 (all terms < 10^999).
C. K. Caldwell, Woodall Numbers.
Brady Haran and Matt Parker, 383 is cool, Numberphile video, 2017.
Eric Weisstein's World of Mathematics, Woodall Number.
FORMULA
a(n) = A002234(n)*2^A002234(n) - 1. - M. F. Hasler, May 10 2017
MATHEMATICA
Select[Table[n 2^n - 1, {n, 300}], PrimeQ] (* Harvey P. Dale, Jul 12 2012 *)
PROG
(PARI) for(n=2, 999, ispseudoprime(p=n*2^n-1)&&print1(p", ")) \\ M. F. Hasler, May 10 2017
(Python)
from sympy import isprime
def auptok(limit):
return list(filter(isprime, (k*2**k-1 for k in range(1, limit+1))))
print(auptok(1000)) # Michael S. Branicky, Jul 23 2021
CROSSREFS
Sequence in context: A187487 A299643 A034192 * A322557 A228699 A159485
KEYWORD
nonn,easy,nice
AUTHOR
N. J. A. Sloane, Dec 30 1999
STATUS
approved

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Last modified June 14 21:35 EDT 2024. Contains 373401 sequences. (Running on oeis4.)