A074886 Numbers k such that sigma(sigma(k) - k) = phi(sigma(k) + k).

14, 110, 274, 435, 1298, 4608, 4646, 5384, 9214, 10154, 10778, 11912, 13035, 13844, 15026, 18698, 21346, 22958, 25642, 26846, 27466, 32078, 34546, 41164, 49570, 77374, 80438, 85875, 112310, 141754, 187610, 196934, 210106, 226094, 296205, 298126, 307874, 309002

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

sigma(sigma(110)-110) = sigma(216-110) = 162; phi(sigma(110)+110) = phi(326) = 162, so 110 is a term of the sequence.

Mathematica

r = {}; Do[d = DivisorSigma[1, n]; If[DivisorSigma[1, d - n] == EulerPhi[d + n], r = Append[r, n]], {n, 1, 10^5}]; r

Crossrefs

Cf. A000010, A000203, A001065, A155085.

Sequence in context: A039629 A349296 A205493 * A294445 A036395 A271561

Adjacent sequences: A074883 A074884 A074885 * A074887 A074888 A074889

Keyword

nonn

Author

Joseph L. Pe, Sep 13 2002

Status

approved