Squares of even pentagonal numbers.

Terms

a(0) =0a(1) =144a(2) =484a(3) =4900a(4) =8464a(5) =30976a(6) =44100a(7) =108900a(8) =141376a(9) =283024a(10) =348100a(11) =611524a(12) =725904a(13) =1166400a(14) =1350244a(15) =2033476a(16) =2310400a(17) =3312400a(18) =3709476a(19) =5116644a(20) =5664400a(21) =7573504a(22) =8305924a(23) =10824100a(24) =11778624a(25) =15023376a(26) =16240900a(27) =20340100