a(n) = Sum_{i=0..floor(n/2)} (-1)^(i+floor(n/2))*T(2i+e), where T(n) are tribonacci numbers (A000073) and e = (1/2)(1-(-1)^n).

A075111

a(n) = Sum_{i=0..floor(n/2)} (-1)^(i+floor(n/2))*T(2i+e), where T(n) are tribonacci numbers (A000073) and e = (1/2)(1-(-1)^n).

Terms

    a(0) =0a(1) =1a(2) =1a(3) =1a(4) =3a(5) =6a(6) =10a(7) =18a(8) =34a(9) =63a(10) =115a(11) =211a(12) =389a(13) =716a(14) =1316a(15) =2420a(16) =4452a(17) =8189a(18) =15061a(19) =27701a(20) =50951a(21) =93714a(22) =172366a(23) =317030a(24) =583110a(25) =1072507a(26) =1972647a(27) =3628263a(28) =6673417a(29) =12274328

External references