login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Slowest-growing sequence of primes p where 1/(p+1) sums to 1 without actually reaching it.
5

%I #15 Jul 13 2015 22:36:16

%S 2,3,5,7,11,29,127,1931,309121,47777896349,76090912606600214447,

%T 120621395443859821620817698234224534627,

%U 63813688766771960235613705494151343867425896610637722399417500492543759703

%N Slowest-growing sequence of primes p where 1/(p+1) sums to 1 without actually reaching it.

%C The sum of 1/(p+1) over p = 2, 3, 5, 7, 11, 23 = A046689 is exactly 1.

%H Robert G. Wilson v, <a href="/A181503/b181503.txt"> Table of n, a(n) for n = 1..17 </a>. [From _Robert G. Wilson v_, Oct 27 2010]

%t a[n_] := a[n] = Block[{sm = Sum[1/(a[i] + 1), {i, n - 1}]}, NextPrime[ Max[ a[n - 1], 1/(1 - sm)]]]; a[0] = 1; Array[a, 15] (* _Robert G. Wilson v_, Oct 27 2010 *)

%Y Similar to A075442. See also A046689.

%K nice,nonn

%O 1,1

%A _Aaron Meyerowitz_, Oct 24 2010

%E a(12) onwards from _Robert G. Wilson v_, Oct 27 2010