OFFSET
1,2
COMMENTS
The least common multiple of an even superperfect number greater than 2 and its arithmetic derivative divided by the number itself, i.e., lcm(A061652(i), A061652(i)')/A061652(i). - Giorgio Balzarotti, Apr 21 2011
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..46
C. K. Caldwell, Top 20 Mersenne primes
Bernhard Helmes, Prime generator f(n)=2n^2-1
George Woltman, Great Internet Mersenne Prime Search
FORMULA
a(n) = (A000043(n+1) - 1)/2.
2^(2*a(n) + 1) - 1 = A000668(n+1). - M. F. Hasler, Jan 27 2020
MATHEMATICA
(MersennePrimeExponent[Range[2, 47]] - 1)/2 (* Amiram Eldar, Mar 29 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Nov 02 2008
EXTENSIONS
Term for the 39th Mersenne prime added by Roderick MacPhee, Oct 05 2009
Formula and edits from Charles R Greathouse IV, Aug 14 2010
Updated to include 40th Mersenne prime by Michael B. Porter, Nov 26 2010
a(40)-a(42) from Amiram Eldar, Mar 29 2020
STATUS
approved