A060684 - OEIS

%I #16 Jun 25 2015 16:35:45

%S 2,4,6,2,10,12,2,16,18,2,22,4,2,28,30,2,2,36,2,40,42,2,46,6,2,52,4,2,

%T 58,60,2,4,66,2,70,72,2,4,78,2,82,4,2,88,6,2,4,96,2,100,102,2,106,108,

%U 2,112,4,2,6,10,2,4,126,2,130,6,2,136,138,2,2,4,2,148,150,2,4,156,2,6

%N Smallest difference between consecutive divisors (ordered by size) of 2n+1.

%C Successively greater values of a(n) occur when 2n+1 is prime.

%H Reinhard Zumkeller, <a href="/A060684/b060684.txt">Table of n, a(n) for n = 1..10000</a>

%F A060680(2n+1)

%e For n=38, 2n+1=77; divisors={1,7,11,77}; differences={6,4,66}; a(38) = smallest difference = 4.

%t a[n_ ] := Min@@(Drop[d=Divisors[2n+1], 1]-Drop[d, -1])

%t Array[Min[Differences[Divisors[2*#+1]]]&,80] (* _Harvey P. Dale_, Dec 08 2013 *)

%o (Haskell)

%o a060684 = minimum . a193829_row . (+ 1) . (* 2)

%o -- _Reinhard Zumkeller_, Jun 25 2015

%Y Cf. A060680.

%Y Different from A071294.

%Y Cf. A193829, A027750.

%K nonn

%O 1,1

%A _Labos Elemer_, Apr 19 2001

%E Edited by _Dean Hickerson_, Jan 22 2002