A120157 a(1)=13; a(n)=floor((39+sum(a(1) to a(n-1)))/3).

13, 17, 23, 30, 40, 54, 72, 96, 128, 170, 227, 303, 404, 538, 718, 957, 1276, 1701, 2268, 3024, 4032, 5376, 7168, 9558, 12744, 16992, 22656, 30208, 40277, 53703, 71604, 95472, 127296, 169728, 226304, 301738, 402318, 536424, 715232, 953642