[seqfan] Move, add, delete, repeat

[Ali Sada]

Hi everyone,
We have a list of positive integers. We start at 1 and move 1 step to reach 2. We add 1+2 = 3, which will be a(1). 
Then, we delete the 2 from the list since we already used it. Now, the second number on the list becomes 3. We move 3 steps and reach 6. a(2) = 3+6 = 9. We delete the 6 from the list. The next remaining number on the list is 4. We move 4 steps and reach 9. a(3)= 4+9 = 13. And so on.



3, 9, 13, 17, 23, 27, 33, 37, 43, 47, 51, 57, 61, 67, 71, 75,81, 85, 91, 95, 99, 105, 109, 115, 119, 125, 129, 133, 139, 143, 149, 153, 157,163, 167, 173, 177, 183, 187, 191, 197, 201, 207, 211, 215, 221, 225, 231, 235,241, 245, 249, 255, 259, 265, 269, 273, 279, 283, 289, 293, 297, 303, 307, 313,317, 323, 327, 331, 337, 341, 347, 351, 355, 361, 365, 371, 375, 381


I need some help with the exact definition of this sequence. 

Best,
Ali