Sums involving triangle A096815.

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =30a(5) =79a(6) =212a(7) =574a(8) =1588a(9) =4455a(10) =12478a(11) =35377a(12) =100335a(13) =285385a(14) =812648a(15) =2318781a(16) =6620447a(17) =18935754a(18) =54209820a(19) =155482355a(20) =446673973a(21) =1284474758a(22) =3698559438a(23) =10659129412a(24) =30740979089a(25) =88719378807a(26) =256240088606a(27) =740502848865