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A056100
Sigma(n)*Phi(n) + 1 (Mod n).
0
0, 0, 0, 3, 0, 1, 0, 5, 7, 3, 0, 5, 0, 5, 13, 9, 0, 1, 0, 17, 7, 9, 0, 1, 21, 11, 19, 1, 0, 7, 0, 17, 4, 15, 33, 13, 0, 17, 19, 1, 0, 19, 0, 9, 28, 21, 0, 17, 43, 11, 10, 13, 0, 1, 21, 25, 31, 27, 0, 49, 0, 29, 28, 33, 3, 43, 0, 21, 16, 27, 0, 1, 0, 35, 11, 25, 63, 55, 0, 33, 55, 39, 0, 1
OFFSET
1,4
REFERENCES
George E. Andrews, "Number Theory," Dover Publ., NY, 1971, page 85.
MATHEMATICA
Do[Print[Mod[DivisorSigma[1, n]*EulerPhi[n] + 1, n]], {n, 1, 100}] Note that iff n is a prime then Sigma(n)*Phi(n) + 1 = 0 (Mod n).
CROSSREFS
Sequence in context: A046665 A100574 A342122 * A141665 A136689 A359364
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Jul 28 2000
STATUS
approved