a(n) = T(n)^2, where T(n) = A000073(n) is the n-th tribonacci number.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =4a(5) =16a(6) =49a(7) =169a(8) =576a(9) =1936a(10) =6561a(11) =22201a(12) =75076a(13) =254016a(14) =859329a(15) =2907025a(16) =9834496a(17) =33269824a(18) =112550881a(19) =380757169a(20) =1288092100a(21) =4357584144a(22) =14741602225a(23) =49870482489a(24) =168710633536a(25) =570743986576