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

Terms

a(0) =1a(1) =-7a(2) =-23a(3) =-47a(4) =-79a(5) =-119a(6) =-167a(7) =-223a(8) =-287a(9) =-359a(10) =-439a(11) =-527a(12) =-623a(13) =-727a(14) =-839a(15) =-959a(16) =-1087a(17) =-1223a(18) =-1367a(19) =-1519a(20) =-1679a(21) =-1847a(22) =-2023a(23) =-2207a(24) =-2399a(25) =-2599a(26) =-2807a(27) =-3023a(28) =-3247a(29) =-3479