Puzzle: sequence without multiples of 3

[Albert Chan]

Here is the HP-12C code that produce f(n), f(n) < 10^10

Code:

Enter Enter Enter
2 / INTG 2 × − Enter ×    ; n%2
2 − + 2 ÷ +               ; f(n) = n + (n + n%2 − 2) / 2