Third column of A071223.

Terms

a(0) =2a(1) =6a(2) =24a(3) =72a(4) =172a(5) =352a(6) =646a(7) =1094a(8) =1742a(9) =2642a(10) =3852a(11) =5436a(12) =7464a(13) =10012a(14) =13162a(15) =17002a(16) =21626a(17) =27134a(18) =33632a(19) =41232a(20) =50052a(21) =60216a(22) =71854a(23) =85102a(24) =100102a(25) =117002a(26) =135956a(27) =157124a(28) =180672a(29) =206772