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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
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
Sequence in context: A031679 A234679 A191303 * A186849 A107654 A345611
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Sep 04 2017
EXTENSIONS
a(4) from Giovanni Resta, Sep 05 2017
STATUS
approved

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