Column 2 of triangle A359670; a(n) = A359670(n+2,2) for n >= 0.

Terms

a(0) =1a(1) =12a(2) =68a(3) =284a(4) =998a(5) =3092a(6) =8724a(7) =22904a(8) =56679a(9) =133516a(10) =301664a(11) =657368a(12) =1387854a(13) =2849168a(14) =5704476a(15) =11166464a(16) =21415632a(17) =40312176a(18) =74593476a(19) =135864792a(20) =243872632a(21) =431835140a(22) =755039948a(23) =1304589104a(24) =2229192801a(25) =3769452152a(26) =6311385252a(27) =10469412968a(28) =17214152072