Zero followed by partial sums of A133405.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =13a(7) =39a(8) =117a(9) =351a(10) =1054a(11) =3163a(12) =9490a(13) =28470a(14) =85410a(15) =256230a(16) =768691a(17) =2306074a(18) =6918223a(19) =20754669a(20) =62264007a(21) =186792021a(22) =560376064a(23) =1681128193a(24) =5043384580a(25) =15130153740a(26) =45390461220a(27) =136171383660