a(n) = Sum_{k=0..n} (k+1) * A026615(n,k).

Terms

a(0) =1a(1) =3a(2) =10a(3) =30a(4) =78a(5) =189a(6) =440a(7) =999a(8) =2230a(9) =4917a(10) =10740a(11) =23283a(12) =50162a(13) =107505a(14) =229360a(15) =487407a(16) =1032174a(17) =2179053a(18) =4587500a(19) =9633771a(20) =20185066a(21) =42205161a(22) =88080360a(23) =183500775a(24) =381681638a(25) =792723429a(26) =1644167140a(27) =3405774819a(28) =7046430690a(29) =14562623457