A055696 Numbers n such that n | Sigma_2(n) + Phi(n)^2.

1, 2, 6, 182, 330, 850, 2150, 5964, 23028, 85800, 168150, 172250, 179850, 308700, 391300, 484692, 507725, 1098750, 1248148, 1377075, 3105218, 4723500, 9547650, 17353350, 22058792, 37465350, 47094425, 54658450, 110019000, 144820200

Offset

1,2

Comments

sigma_2(n) is the sum of the squares of the divisors of n (A001157).

Links

Table of n, a(n) for n=1..30.

Mathematica

Do[If[Mod[DivisorSigma[2, n]+EulerPhi[n]^2, n]==0, Print[n]], {n, 1, 2*10^6}]

Crossrefs

Sequence in context: A203430 A298883 A252740 * A158096 A345726 A302344

Adjacent sequences: A055693 A055694 A055695 * A055697 A055698 A055699

Keyword

nonn

Author

Robert G. Wilson v, Jun 09 2000

Extensions

a(21)-a(30) from Donovan Johnson, Feb 13 2010

Status

approved