This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 C. K. Caldwell, Top 20 Mersenne primes 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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