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A275998
Numbers n such that phi(n^2-1) = phi(n^2+1).
0
3, 27, 267, 8820000
OFFSET
1,1
COMMENTS
No other terms below 10^8. - Michel Marcus, Aug 17 2016
EXAMPLE
3 is a term because phi(3^2-1) = phi(3^2+1).
MATHEMATICA
Select[Range@10000000, EulerPhi@(#^2 - 1) == EulerPhi[#^2 + 1] &] (* Vincenzo Librandi, Aug 18 2016 *)
PROG
(PARI) isok(n) = eulerphi(n^2-1) == eulerphi(n^2+1); \\ Michel Marcus, Aug 16 2016
(Magma) [n: n in [2..100000] | EulerPhi(n^2-1) eq EulerPhi(n^2+1)]; // Vincenzo Librandi, Aug 18 2016
CROSSREFS
Sequence in context: A373818 A026294 A199688 * A098401 A355363 A011544
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Aug 16 2016
STATUS
approved