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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A068484 Numbers n such that n divides phi(n)^2 + sigma(n)^2. 1
1, 2, 10, 45, 65, 180, 212, 222, 369, 588, 810, 864, 1274, 1521, 1836, 2548, 2940, 3114, 3552, 4770, 5496, 5684, 6027, 6642, 8820, 9140, 10464, 10614, 13311, 14688, 15210, 20737, 21600, 22776, 26900, 27000, 27270, 28476, 28518, 42212, 42336 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(275) has n value > 7*10^7. - G. C. Greubel, Oct 15 2018

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..274

MAPLE

with(numtheory): select(n->modp(phi(n)^2+sigma(n)^2, n)=0, [$1..42500]); # Muniru A Asiru, Oct 16 2018

MATHEMATICA

Select[Range[7000], IntegerQ[(EulerPhi[#]^2 + DivisorSigma[1, #]^2)/#] &] (* G. C. Greubel, Oct 15 2018 *)

PROG

(GAP) Filtered([1..42500], n->(Phi(n)^2+Sigma(n)^2) mod n=0); # Muniru A Asiru, Oct 16 2018

CROSSREFS

Cf. A072861 (sigma(n)^2), A127473 (phi(n)^2).

Sequence in context: A065805 A145239 A068561 * A192704 A005963 A140588

Adjacent sequences:  A068481 A068482 A068483 * A068485 A068486 A068487

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Mar 10 2002

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 5 20:10 EDT 2020. Contains 335473 sequences. (Running on oeis4.)