A120151 a(1)=5; a(n)=floor((15+sum(a(1) to a(n-1)))/3).

5, 6, 8, 11, 15, 20, 26, 35, 47, 62, 83, 111, 148, 197, 263, 350, 467, 623, 830, 1107, 1476, 1968, 2624, 3499, 4665, 6220, 8293, 11058, 14744, 19658, 26211, 34948, 46597, 62130, 82840, 110453, 147271, 196361, 261815, 349086