a(n) = 5*(n^2 - n + 2)/2.

Terms

a(0) =5a(1) =5a(2) =10a(3) =20a(4) =35a(5) =55a(6) =80a(7) =110a(8) =145a(9) =185a(10) =230a(11) =280a(12) =335a(13) =395a(14) =460a(15) =530a(16) =605a(17) =685a(18) =770a(19) =860a(20) =955a(21) =1055a(22) =1160a(23) =1270a(24) =1385a(25) =1505a(26) =1630a(27) =1760a(28) =1895a(29) =2035