a(n) = 4*n^3 - 6*n^2 + 1.

Terms

a(0) =1a(1) =-1a(2) =9a(3) =55a(4) =161a(5) =351a(6) =649a(7) =1079a(8) =1665a(9) =2431a(10) =3401a(11) =4599a(12) =6049a(13) =7775a(14) =9801a(15) =12151a(16) =14849a(17) =17919a(18) =21385a(19) =25271a(20) =29601a(21) =34399a(22) =39689a(23) =45495a(24) =51841a(25) =58751a(26) =66249a(27) =74359a(28) =83105a(29) =92511