a(n) = 25*(n + 1)*(4*n + 3)*(5*n + 4)/3.

Terms

a(0) =100a(1) =1050a(2) =3850a(3) =9500a(4) =19000a(5) =33350a(6) =53550a(7) =80600a(8) =115500a(9) =159250a(10) =212850a(11) =277300a(12) =353600a(13) =442750a(14) =545750a(15) =663600a(16) =797300a(17) =947850a(18) =1116250a(19) =1303500a(20) =1510600a(21) =1738550a(22) =1988350a(23) =2261000a(24) =2557500a(25) =2878850a(26) =3226050a(27) =3600100a(28) =4002000a(29) =4432750