http://oeis.org/A276260 |

The mesmerizing thing about this sequence is the fact that there are only 9 known terms of it so far, and if a 10th term exists, it must be greater than 10^9.

The other sequence that I submitted was the one I talked about here, which is now sequence A276290 in OEIS.

The interesting thing to me is the fact that so far no counter example has been found to my conjecture that if n is the product of two odd primes p and q and p = 3 then neither p nor q is in the trajectory of n+1 under the Collatz 3x+1 map.

This makes me wonder if there are primes other than 3 for which this conjecture also appears to be true.