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 A096060 (2^(p-1)-1)/(3*p) where p = prime(n). 7
 1, 3, 31, 105, 1285, 4599, 60787, 3085465, 11545611, 619094385, 8939118925, 34093383807, 499069107643, 28324525958305, 1628420204246959, 6300117511512825, 367099384551433863, 5542683665339959171 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,2 LINKS T. D. Noe, Table of n, a(n) for n=3..100 P. Terzich, On the Form of Mersenne Numbers, vixra:1202.0024. - From N. J. A. Sloane, Jun 20 2012 FORMULA a(n) = A001045(prime(n)-1)/prime(n). a(n) = A007663(n)/3 for n>2. - Alexander Adamchuk, Jun 08 2006 a(n) = A002450((p-1)/2)/p, for p=prime(n) and n>=3. - Roderick MacPhee, Sep 29 2014 MAPLE seq((2^(ithprime(n)-1)-1)/(3*ithprime(n)), n=3..50); # Robert Israel, Oct 14 2014 MATHEMATICA Table[(2^(Prime[n]-1)-1)/(3*Prime[n]), {n, 3, 22}] (* Alexander Adamchuk, Jun 08 2006 *) Table[(2^(n-1)-1)/(3n), {n, Prime[Range[3, 20]]}] (* Harvey P. Dale, Dec 27 2014 *) PROG (PARI) b(n) = (4^n - 1)/3; a(n) = p = prime(n); b((p-1)/2)/p; \\ Michel Marcus, Sep 30 2014 (MAGMA)  [(2^(NthPrime(n)-1)-1) div (3*NthPrime(n)): n in [3..25]]; // Vincenzo Librandi, Oct 15 2014 CROSSREFS Cf. A001045, A002450, A007663. Sequence in context: A077547 A104312 A107197 * A199367 A295534 A119682 Adjacent sequences:  A096057 A096058 A096059 * A096061 A096062 A096063 KEYWORD nonn AUTHOR Amarnath Murthy, Jun 18 2004 EXTENSIONS More terms from Alexander Adamchuk, Jun 08 2006 Formula using A001045 corrected by Jonathan Sondow, Jul 19 2010 STATUS approved

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Last modified March 25 22:28 EDT 2019. Contains 321477 sequences. (Running on oeis4.)