a(n) = (5*n + 3)*(5*n + 4)*(5*n + 5)/6.

Terms

a(0) =10a(1) =120a(2) =455a(3) =1140a(4) =2300a(5) =4060a(6) =6545a(7) =9880a(8) =14190a(9) =19600a(10) =26235a(11) =34220a(12) =43680a(13) =54740a(14) =67525a(15) =82160a(16) =98770a(17) =117480a(18) =138415a(19) =161700a(20) =187460a(21) =215820a(22) =246905a(23) =280840a(24) =317750a(25) =357760a(26) =400995a(27) =447580a(28) =497640a(29) =551300