A026278 a(n) = greatest k such that s(k) = n, where s = A026276.

4, 6, 8, 11, 14, 17, 19, 22, 24, 27, 29, 32, 35, 37, 40, 43, 45, 48, 51, 53, 56, 58, 61, 64, 66, 69, 71, 74, 77, 79, 82, 84, 87, 90, 92, 95, 98, 100, 103, 105, 108, 111, 113, 116, 119, 121, 124, 126, 129, 132, 134, 137, 140, 142, 145