a(n) = Sum_{k=1..n-1} lcm(k,n-k).

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =8a(5) =20a(6) =21a(7) =56a(8) =60a(9) =96a(10) =105a(11) =220a(12) =152a(13) =364a(14) =301a(15) =360a(16) =464a(17) =816a(18) =549a(19) =1140a(20) =760a(21) =1036a(22) =1221a(23) =2024a(24) =1196a(25) =2200a(26) =2041a(27) =2484a(28) =2184a(29) =4060