A333169 a(n) = phi(n^2 + 1), where phi is the Euler totient function (A000010).

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

Author

Amiram Eldar, Mar 09 2020

Keywords

• nonn

Examples

			a(0) = phi(0^2 + 1) = phi(1) = 1.
		

References

• Steven R. Finch, Mathematical Constants II, Encyclopedia of Mathematics and Its Applications, Cambridge University Press, Cambridge, 2018, p. 166.

Links

• Amiram Eldar, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A000010, A002522, A067720, A193432, A193433, A333167.

Programs

Mathematica

Table[EulerPhi[k^2 + 1], {k, 0, 100}]

PARI

a(n) = eulerphi(n^2+1); \\ Michel Marcus, Mar 10 2020

Formula

a(n) = A000010(A002522(n)).