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A146768 a(n) = numbers k such that 2(2^k)^2 - 1 = (n+1)-th Mersenne Prime = A000668(n+1). 1
1, 2, 3, 6, 8, 9, 15, 30, 44, 53, 63, 260, 303, 639, 1101, 1140, 1608, 2126, 2211, 4844, 4970, 5606, 9968, 10850, 11604, 22248, 43121, 55251, 66024, 108045, 378419, 429716, 628893, 699134, 1488110, 1510688, 3486296, 6733458, 10498005 (list; graph; refs; listen; history; text; internal format)
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

Table of n, a(n) for n=1..39.

C. K. Caldwell, Top 20 Mersenne primes

Helmes B., 9. Mersenne Numbers and the polynomial f(x)=2x^2-1

George Woltman, Great Internet Mersenne Prime Search

FORMULA

a(n) = (A000043(n+1) - 1)/2.

PROG

(PARI) forprime(x=1, , if(ispower(x+1) && isprimepower(x+1) && valuation(x+1, 4)==logint(x+1, 4), print1(logint(x+1, 4), ", "))) \\ Roderick MacPhee, Dec 17 2016

CROSSREFS

Sequence in context: A099381 A289943 A089437 * A211370 A122479 A285306

Adjacent sequences:  A146765 A146766 A146767 * A146769 A146770 A146771

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

STATUS

approved

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Last modified December 6 18:03 EST 2019. Contains 329809 sequences. (Running on oeis4.)