a(n) = floor( n*(n-1)*(n-2)/10 ).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =6a(6) =12a(7) =21a(8) =33a(9) =50a(10) =72a(11) =99a(12) =132a(13) =171a(14) =218a(15) =273a(16) =336a(17) =408a(18) =489a(19) =581a(20) =684a(21) =798a(22) =924a(23) =1062a(24) =1214a(25) =1380a(26) =1560a(27) =1755a(28) =1965a(29) =2192