Partial sums of A014138.

Terms

a(0) =1a(1) =4a(2) =12a(3) =34a(4) =98a(5) =294a(6) =919a(7) =2974a(8) =9891a(9) =33604a(10) =116103a(11) =406614a(12) =1440025a(13) =5147876a(14) =18550572a(15) =67310938a(16) =245716094a(17) =901759950a(18) =3325066996a(19) =12312494462a(20) =45766188948a(21) =170702447074a(22) =638698318850