G.f.: x * (d/dx) x * Product_{k>=1} (1 + x^k)^(a(k)/k).

Terms

a(0) =1a(1) =2a(2) =3a(3) =8a(4) =15a(5) =36a(6) =84a(7) =200a(8) =468a(9) =1130a(10) =2717a(11) =6576a(12) =15938a(13) =38780a(14) =94485a(15) =230816a(16) =564553a(17) =1383318a(18) =3393742a(19) =8336960a(20) =20502216a(21) =50472928a(22) =124369832a(23) =306729456a(24) =757078000a(25) =1870040822a(26) =4622317812a(27) =11432698704a(28) =28294211920a(29) =70063292310