a(n) = n^2 - floor( n/2 ).

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =14a(5) =23a(6) =33a(7) =46a(8) =60a(9) =77a(10) =95a(11) =116a(12) =138a(13) =163a(14) =189a(15) =218a(16) =248a(17) =281a(18) =315a(19) =352a(20) =390a(21) =431a(22) =473a(23) =518a(24) =564a(25) =613a(26) =663a(27) =716a(28) =770a(29) =827