%I A083531
%S A083531 2,1,2,1,1,4,1,1,1,3,2,4,4,2,1,1,4,2,1,1,2,2,4,6,2,1,3,2,1,5,4,2,4,2,4,
%T A083531 6,1,2,3,2,4,2,4,2,2,2,6,1,3,2,1,1,4,1,5,2,4,6,2,4,2,2,2,2,4,3,3,2,4,2,
%U A083531 1,3,6,2,1,3,2,4,6,2,4,1,5,2,4,2,4,6,2,6,4,3,1,2,2,4,2,4,2,6,2,2,2,4,6
%N A083531 First difference sequence of A002191. Differences between possible values 
               for sum of divisors of n.
%e A083531 8 and 12 are the 6th and 7th possible values for
%e A083531 sigma[x],since are sum of divisors of x=7 and x=11
%e A083531 respectively, while 9,10,11 are impossible ones
%e A083531 so 12-8=4=a(6)=A002191[7]-A002191[6].
%t A083531 t=Table[DivisorSigma[1, w], {w, 1, 25000}]; u=Union[%]; Delete[u-RotateRight[u], 
               1]
%Y A083531 Cf. A002191, A007609, A007369, A083532-A083536.
%Y A083531 Sequence in context: A134303 A078997 A024680 this_sequence A003417 A158986 
               A079900
%Y A083531 Adjacent sequences: A083528 A083529 A083530 this_sequence A083532 A083533 
               A083534
%K A083531 nonn
%O A083531 1,1
%A A083531 Labos E. (labos(AT)ana.sote.hu), May 20 2003