Number of (w,x,y,z) with all terms in {1,...,n} and |w-x|<|x-y|+|y-z|.

Terms

a(0) =0a(1) =0a(2) =8a(3) =48a(4) =168a(5) =428a(6) =916a(7) =1728a(8) =2992a(9) =4840a(10) =7440a(11) =10960a(12) =15608a(13) =21588a(14) =29148a(15) =38528a(16) =50016a(17) =63888a(18) =80472a(19) =100080a(20) =123080a(21) =149820a(22) =180708a(23) =216128a(24) =256528a(25) =302328a(26) =354016a(27) =412048a(28) =476952a(29) =549220