G.f.: Product_{k>=1} 1/(1-x^k)^(2*k+3).

Terms

a(0) =1a(1) =5a(2) =22a(3) =79a(4) =259a(5) =777a(6) =2201a(7) =5911a(8) =15239a(9) =37865a(10) =91224a(11) =213741a(12) =488759a(13) =1093173a(14) =2396934a(15) =5160756a(16) =10928181a(17) =22787949a(18) =46848176a(19) =95046026a(20) =190466354a(21) =377295743a(22) =739319876a(23) =1433974869a(24) =2754597217a(25) =5243308562a(26) =9894376295a(27) =18517966608a(28) =34386781020a(29) =63378252332