The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A291869 Numbers n such that sigma(phi(n)) - phi(n) = n + phi(sigma(n)-n); that is, f(g(n)) - g(f(n)) = n where f = A001065 and g = A000010. 1
 52298, 88694, 13868696, 18816288938 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(5) > 45*10^9. - Giovanni Resta, Sep 05 2017 LINKS Table of n, a(n) for n=1..4. EXAMPLE 52298 is a term because phi(sigma(52298) - 52298) = phi(27382) = 13690, sigma(phi(52298)) - phi(52298) = sigma(25740) - 25740 = 65988 and 65988 - 13690 = 52298. PROG (PARI) a001615(n) = sigma(n)-n; isok(n) = a001615(eulerphi(n))==n+eulerphi(a001615(n)); CROSSREFS Cf. A000010, A001065, A062401, A062402. Sequence in context: A031679 A234679 A191303 * A186849 A107654 A345611 Adjacent sequences: A291866 A291867 A291868 * A291870 A291871 A291872 KEYWORD nonn,more AUTHOR Altug Alkan, Sep 04 2017 EXTENSIONS a(4) from Giovanni Resta, Sep 05 2017 STATUS approved

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

Last modified June 22 04:21 EDT 2024. Contains 373561 sequences. (Running on oeis4.)