Sum of squares of tribonacci numbers (A000073).

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =6a(5) =22a(6) =71a(7) =240a(8) =816a(9) =2752a(10) =9313a(11) =31514a(12) =106590a(13) =360606a(14) =1219935a(15) =4126960a(16) =13961456a(17) =47231280a(18) =159782161a(19) =540539330a(20) =1828631430a(21) =6186215574a(22) =20927817799a(23) =70798300288a(24) =239508933824a(25) =810252920400