A025576 a(n) = T(n,[ n/2 ]+1), where T is the array defined in A025564.
1, 4, 10, 22, 61, 120, 356, 665, 2058, 3732, 11892, 21153, 68860, 120835, 399828, 694590, 2328066, 4013088, 13591364, 23284424, 79538750, 135580865, 466489520, 791862354, 2741310614, 4637009300, 16137748980, 27215510265, 95152639095, 160053426720
Offset: 1