T(n,0) + T(n,1) + ... + T(n,n), T given by A026568.

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =30a(5) =75a(6) =189a(7) =478a(8) =1211a(9) =3076a(10) =7818a(11) =19901a(12) =50680a(13) =129179a(14) =329383a(15) =840336a(16) =2144540a(17) =5474889a(18) =13980493a(19) =35709394a(20) =91228015a(21) =233108456a(22) =595740568a(23) =1522725379a(24) =3892624055a(25) =9952119054a(26) =25446913766a(27) =65072487645