G.f.: Product_{k>=1} 1/(1-x^k)^(5*k).

Terms

a(0) =1a(1) =5a(2) =25a(3) =100a(4) =370a(5) =1251a(6) =4005a(7) =12150a(8) =35400a(9) =99365a(10) =270353a(11) =715025a(12) =1844650a(13) =4652075a(14) =11494605a(15) =27872056a(16) =66428295a(17) =155809600a(18) =360079225a(19) =820715820a(20) =1846583863a(21) =4104572975a(22) =9019869125a(23) =19608423750a(24) =42193733645a(25) =89917531549a(26) =189863358445a(27) =397401303850