Volume of sphere (rounded down) with the diameter equal to n.

Terms

a(0) =0a(1) =4a(2) =14a(3) =33a(4) =65a(5) =113a(6) =179a(7) =268a(8) =381a(9) =523a(10) =696a(11) =904a(12) =1150a(13) =1436a(14) =1767a(15) =2144a(16) =2572a(17) =3053a(18) =3591a(19) =4188a(20) =4849a(21) =5575a(22) =6370a(23) =7238a(24) =8181a(25) =9202a(26) =10305a(27) =11494a(28) =12770a(29) =14137