A207667 Numbers n such that phi(n) divides n+2.

1, 2, 4, 6, 10, 30, 70, 510, 2590, 131070, 3359230, 167247870, 8589934590, 13985925344264190

Offset: 1

Author

José María Grau Ribas, Feb 19 2012

Keywords

• nonn
• more
• hard

Comments

Contains 2 * A203966 as a subsequence. - Max Alekseyev, Oct 27 2023

Crossrefs

Cf. A000010, A050474, A207574, A202855, A203966.

Programs

Mathematica

Select[Range[50000000],Divisible[#+2,EulerPhi[#]]&]

Extensions

a(12)-a(13) from Donovan Johnson, Mar 01 2012

a(14) from Max Alekseyev, Oct 27 2023