A080574 a(1)=1, a(n)=a(n-1)+1 if n is odd and already in the sequence, a(n)=a(n-1)+2 if n is even and already in the sequence, a(n)=a(n-1)+3 otherwise.

1, 4, 7, 9, 12, 15, 16, 19, 20, 23, 26, 28, 31, 34, 35, 37, 40, 43, 44, 46, 49, 52, 53, 56, 59, 61, 64, 66, 69, 72, 73, 76, 79, 81, 82, 85, 86, 89, 92, 94, 97, 100, 101, 103, 106, 108, 111, 114, 115, 118, 121, 123, 124, 127, 130, 132, 135, 138, 139, 142