a(n) = n*T(n), where T(n) = A000073(n) = n-th tribonacci number.

Terms

a(0) =0a(1) =0a(2) =2a(3) =3a(4) =8a(5) =20a(6) =42a(7) =91a(8) =192a(9) =396a(10) =810a(11) =1639a(12) =3288a(13) =6552a(14) =12978a(15) =25575a(16) =50176a(17) =98056a(18) =190962a(19) =370747a(20) =717800a(21) =1386252a(22) =2671130a(23) =5136291a(24) =9857856a(25) =18886900a(26) =36127962a(27) =69005439a(28) =131621560a(29) =250735856