Sum of distinct products i*j*k with 1 <= i, j, k <= n.

Terms

a(0) =1a(1) =15a(2) =90a(3) =310a(4) =990a(5) =2220a(6) =5300a(7) =9660a(8) =17130a(9) =28670a(10) =52848a(11) =75696a(12) =128541a(13) =183393a(14) =257628a(15) =344316a(16) =529038a(17) =683316a(18) =1001110a(19) =1256010a(20) =1607004a(21) =2049490a(22) =2837700a(23) =3330636a(24) =4177186a(25) =5150340a(26) =6273810a(27) =7432702a(28) =9779991a(29) =11124711