Sum{T(n,k)}, k = 0,1,...,n, where T is the array defined in A026082.

Terms

a(0) =2a(1) =4a(2) =8a(3) =15a(4) =42a(5) =127a(6) =376a(7) =1122a(8) =3344a(9) =9980a(10) =29796a(11) =89007a(12) =265986a(13) =795147a(14) =2377744a(15) =7112065a(16) =21277698a(17) =63670773a(18) =190560180a(19) =570416805a(20) =1707707142a(21) =5113158165a(22) =15311384784a(23) =45854766744a(24) =137339426436a(25) =411379964442