A083587 4*3^n/3-5*0^n/6-(n-1)2^(n-1).

1, 4, 10, 28, 84, 260, 812, 2532, 7852, 24196, 74124, 225956, 686060, 2076612, 6270796, 18902500, 56904108, 171138308, 514332428, 1544963364, 4639084396, 13926166084, 41797372620, 125431963748, 376379777324, 1129315492740