The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A291788 Numbers n whose trajectory under the map k -> (psi(k)+phi(k))/2 (A291784) grows without limit. 4

%I

%S 45,48,50,55,56,60,68,69,70,72,74,75,76,77,78,80,84,85,86,87,88,90,91,

%T 92,93,94,95,96,98,99,102,104,105,108,111,112,115,116,117,118,119,120,

%U 122,123,124,126,133,134,135,136,140,141,142,143,144,145,146,147,152

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

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

%C 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

%Y Cf. A291784, A291785, A291786, A291787.

%K nonn,more

%O 1,1

%A _N. J. A. Sloane_, Sep 03 2017, based on data supplied by _Hans Havermann_.

%E Terms 104 to 152 added by _N. J. A. Sloane_, Sep 24 2017

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 10 19:18 EDT 2021. Contains 342853 sequences. (Running on oeis4.)