Duplicate of A004255.

Terms

a(0) =0a(1) =1a(2) =3a(3) =9a(4) =25a(5) =60a(6) =126a(7) =238a(8) =414a(9) =675a(10) =1045a(11) =1551a(12) =2223a(13) =3094a(14) =4200a(15) =5580a(16) =7276a(17) =9333a(18) =11799a(19) =14725a(20) =18165a(21) =22176a(22) =26818a(23) =32154a(24) =38250a(25) =45175a(26) =53001a(27) =61803a(28) =71659a(29) =82650