Column three of the triangular matrix in A135835.

Terms

a(0) =3a(1) =22a(2) =82a(3) =254a(4) =677a(5) =1692a(6) =3972a(7) =9052a(8) =19975a(9) =43394a(10) =92534a(11) =195546a(12) =408489a(13) =848584a(14) =1749544a(15) =3594104a(16) =7345547a(17) =14976366a(18) =30424986a(19) =61706038a(20) =124829101a(21) =252226676a(22) =508704716a(23) =1025115156a(24) =2062984719a(25) =4149086938a(26) =8336437438a(27) =16742227730a(28) =33599246513a(29) =67406551968