

A291788


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


4



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
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OFFSET

1,1


COMMENTS

See A291787 (where A291787(m) = 2*A291787(m7) 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


LINKS

Table of n, a(n) for n=1..59.


CROSSREFS

Cf. A291784, A291785, A291786, A291787.
Sequence in context: A031064 A183983 A116334 * A291787 A257410 A306103
Adjacent sequences: A291785 A291786 A291787 * A291789 A291790 A291791


KEYWORD

nonn,more


AUTHOR

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


EXTENSIONS

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


STATUS

approved



