login

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

n + (smallest prime-factor of n+1).
1

%I #7 Apr 01 2014 20:10:19

%S 3,5,5,9,7,13,9,11,11,21,13,25,15,17,17,33,19,37,21,23,23,45,25,29,27,

%T 29,29,57,31,61,33,35,35,39,37,73,39,41,41,81,43,85,45,47,47,93,49,55,

%U 51,53,53,105,55,59,57,59,59,117,61,121,63,65,65,69,67,133,69,71,71

%N n + (smallest prime-factor of n+1).

%C a(n) = n + A020639(n+1).

%H Reinhard Zumkeller, <a href="/A087349/b087349.txt">Table of n, a(n) for n = 1..10000</a>

%o (Haskell)

%o a087349 n = a020639 (n + 1) + n -- _Reinhard Zumkeller_, Mar 31 2014

%Y A061228(n) - 1.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Oct 20 2003