Difference between A007678(2n)/(2n) and (n-1)^2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =6a(5) =12a(6) =32a(7) =57a(8) =73a(9) =144a(10) =210a(11) =255a(12) =394a(13) =516a(14) =520a(15) =833a(16) =1032a(17) =1182a(18) =1518a(19) =1809a(20) =1927a(21) =2500a(22) =2904a(23) =3205a(24) =3836a(25) =4368a(26) =4768a(27) =5577a(28) =6258a(29) =6550