A077815 2^phi(n) mod n^2, where phi is Euler's totient function A000010.

0, 2, 4, 4, 16, 4, 15, 16, 64, 16, 56, 16, 40, 64, 31, 0, 222, 64, 58, 256, 127, 56, 392, 256, 451, 40, 433, 176, 30, 256, 187, 0, 958, 800, 841, 208, 38, 780, 586, 1536, 944, 568, 1076, 1200, 91, 392, 2069, 1024, 2157, 1076, 1021, 1600, 1909, 2620, 826, 2752

Offset: 1

Author

Reinhard Zumkeller, Nov 17 2002

Keywords

• nonn

Examples

			a(42) = 2^phi(42) mod 42*42 = 2^phi(2*3*7) mod 1764 = 2^(42*(1-1/2)*(1-1/3)*(1-1/7)) mod 1764 = 2^12 mod 1764 = 4096 mod 1764 = 568.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A077816, A000010, A000290.

Programs

Mathematica

PowerMod[2,EulerPhi[#],#^2]&/@Range[60] (* Harvey P. Dale, Dec 04 2021 *)

PARI

a(n)=lift(Mod(2,n^2)^eulerphi(n)) \\ Charles R Greathouse IV, Feb 21 2013