Sum of squares of first n tetranacci numbers (A000288).

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =20a(5) =69a(6) =238a(7) =863a(8) =3264a(9) =12100a(10) =44861a(11) =166662a(12) =619591a(13) =2301800a(14) =8551800a(15) =31774561a(16) =118060082a(17) =438649107a(18) =1629796276a(19) =6055504952a(20) =22499207241a(21) =83595676570a(22) =310599326171