A125685 Primes in A125683(n) in order of their occurrence.

5, 11, 2, 79, 331, 479, 5297, 70061, 69203, 8960447, 45083347, 1031626241, 15484789693, 15537907043, 64166447971, 3979714828967, 3988907823167, 27918983997629, 598858179567591121853, 31710728461561839214229

Offset

1,1

Comments

Corresponding numbers k such that A125683(k) is prime are listed in A125684.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..65

Formula

a(n) = A125683(A125684(n)).

Example

A125683(n) begins {1,1,5,11,2,79,331,479,493,5297,2701,69071,70061,...}.
Thus a(1) = 5 because 5 is the first prime in A125683.
a(2)-a(6) = {11,2,79,331,479} because A125683(k) is prime for 3<k<9.

Mathematica

Select[Table[Numerator[Sum[(-1)^(k+1)*1/(k(k+1)), {k, 1, n}]], {n, 1, 100}], PrimeQ]

Crossrefs

Cf. A125683, A125684.

Sequence in context: A111118 A159199 A125683 * A098147 A100298 A066461

Adjacent sequences: A125682 A125683 A125684 * A125686 A125687 A125688

Keyword

nonn

Author

Alexander Adamchuk, Nov 30 2006

Status

approved