A066152 Numbers k such that phi(k) = sigma(k+1) - sigma(k).

2, 459, 17835, 34089, 55419, 61183, 180785, 194139, 248501, 385671, 907323, 988455, 1374735, 1407413, 1408253, 1452135, 1749087, 2451727, 3026705, 3263585, 3831487, 6541695, 7633989, 9336785, 12750833, 16543433, 16573963, 21248201

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..70

Example

phi(459) = 288 = 1008 - 720 = sigma(460) - sigma(459). [corrected by Harry J. Smith, Feb 03 2010]

Mathematica

Select [Range[1, 10^6], EulerPhi[ # ] == DivisorSigma[1, # + 1] - DivisorSigma[1, # ] & ]

Prog

(PARI) isok(k) = { eulerphi(k) == sigma(k + 1) - sigma(k) } \\ Harry J. Smith, Feb 03 2010

Crossrefs

Sequence in context: A012734 A363699 A099686 * A112862 A094484 A062620

Adjacent sequences: A066149 A066150 A066151 * A066153 A066154 A066155

Keyword

nonn

Author

Joseph L. Pe, Dec 13 2001

Extensions

More terms from Robert G. Wilson v, Dec 27 2001

a(25)-a(28) from Harry J. Smith, Feb 03 2010

Status

approved