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A333169
a(n) = phi(n^2 + 1), where phi is the Euler totient function (A000010).
5
1, 1, 4, 4, 16, 12, 36, 20, 48, 40, 100, 60, 112, 64, 196, 112, 256, 112, 240, 180, 400, 192, 384, 208, 576, 312, 676, 288, 624, 420, 832, 432, 800, 432, 1056, 612, 1296, 544, 1088, 760, 1600, 812, 1408, 720, 1776, 1012, 2016, 768, 1840, 1200, 2400, 1300, 2160
OFFSET
0,3
REFERENCES
Steven R. Finch, Mathematical Constants II, Encyclopedia of Mathematics and Its Applications, Cambridge University Press, Cambridge, 2018, p. 166.
LINKS
FORMULA
a(n) = A000010(A002522(n)).
EXAMPLE
a(0) = phi(0^2 + 1) = phi(1) = 1.
MATHEMATICA
Table[EulerPhi[k^2 + 1], {k, 0, 100}]
PROG
(PARI) a(n) = eulerphi(n^2+1); \\ Michel Marcus, Mar 10 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 09 2020
STATUS
approved