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!)
 A319314 Numbers k such that 2^phi(k) == phi(k)^2 (mod k^2). 0
 1, 3, 4, 5, 6, 8, 10, 12, 384, 640, 768, 896, 960, 24576, 49152, 950272, 1425408, 1572864, 3145728, 10485760, 19398656, 65011712, 100663296, 110057537, 201326592, 220115074, 671088640, 1879048192 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Sequence is infinite, i.e., 3*2^(3*(t-1)-(-1)^t) is a term for all t > 0. Prime terms (5, 110057537, ...) are in A246568 based on case A = +1. LINKS PROG (PARI) isok(n) = Mod(2, n^2)^eulerphi(n)==eulerphi(n)^2; (MAGMA) [1] cat [n: n in [1..10^6] | 2^EulerPhi(n) mod n^2 eq EulerPhi(n)^2]; // Vincenzo Librandi, Sep 20 2018 CROSSREFS Cf. A077815, A077816, A246568, A292544. Sequence in context: A062514 A065875 A197639 * A167057 A100585 A023367 Adjacent sequences:  A319311 A319312 A319313 * A319315 A319316 A319317 KEYWORD nonn,more AUTHOR Altug Alkan, Sep 17 2018 STATUS approved

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 8 05:55 EDT 2020. Contains 333312 sequences. (Running on oeis4.)