%I A111694
%S A111694 0,8,26,57,104,170,258,371,512,684,890,1133,1416,1742,2114,2535,3008,
%T A111694 3536,4122,4769,5480,6258,7106,8027,9024,10100,11258,12501,13832,15254,
%U A111694 16770,18383,20096,21912,23834,25865,28008,30266,32642,35139,37760
%N A111694 a(1) = 1+2-3 = 0, a(2) = 4+5+6-7 = 8, a(3) = 8+9+10+11-12 = 26, a(4) 
               = 13+14+15+16+17-18 = 57, ...
%F A111694 (n^3 + 4n^2 - 3n - 2)/2.
%p A111694 seq(sum(j,j=binomial(n+1,2)+n-1..binomial(n+2,2)+n-2) - binomial(n+2,
               2)-n+1,n=1..50); (Deutsch)
%t A111694 Table[(n^3 + 4n^2 - 3n - 2)/2, {n, 41}] (* Robert G. Wilson v *)
%Y A111694 Cf. A034856.
%Y A111694 Sequence in context: A126264 A085690 A005897 this_sequence A129111 A002413 
               A163121
%Y A111694 Adjacent sequences: A111691 A111692 A111693 this_sequence A111695 A111696 
               A111697
%K A111694 nonn
%O A111694 1,2
%A A111694 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 17 2005
%E A111694 Edited and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu) and 
               Robert G. Wilson v (rgwv(at)rgwv.com), Aug 27 2005