A291788 Numbers n whose trajectory under the map k -> (psi(k)+phi(k))/2 (A291784) grows without limit.

45, 48, 50, 55, 56, 60, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 102, 104, 105, 108, 111, 112, 115, 116, 117, 118, 119, 120, 122, 123, 124, 126, 133, 134, 135, 136, 140, 141, 142, 143, 144, 145, 146, 147, 152

Offset: 1

Author

N. J. A. Sloane, Sep 03 2017, based on data supplied by Hans Havermann

Keywords

• nonn
• more

Comments

See A291787 (where A291787(m) = 2*A291787(m-7) for m >= 35) for the trajectory of 45.

There is a similar proof that all the terms from 48 though 152 have a trajectory that merges with the trajectory of 45, and so doubles every 7 steps after a certain point. For example, the trajectory of 152 reaches 2^106*33 at step 390, is 2^107*33 at step 397, and thereafter doubles every 7 steps.- N. J. A. Sloane, Sep 24 2017

Crossrefs

Cf. A291784, A291785, A291786, A291787.

Extensions

Terms 104 to 152 added by N. J. A. Sloane, Sep 24 2017