A082955 Numbers k such that sigma(k*phi(k)) = sigma(k)^2.

1, 87, 1257, 42921, 65307, 68037, 89067, 112803, 116619, 186231, 252417, 350283, 356259, 380559, 435993, 477723, 492771, 527781, 635259, 672051, 708111, 866379, 991479, 1062723, 1078509, 1347699, 1352199, 1353873, 1449363, 1561431, 1838019

Offset

1,2

Links

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

Mathematica

Select[Range[2000000], DivisorSigma[1, # EulerPhi[#]]== DivisorSigma[1, #]^2&]  (* Harvey P. Dale, Mar 27 2011 *)

Prog

(PARI) for(n=1, 2000000, if(sigma(n*eulerphi(n))==sigma(n)^2, print1(n, ", ")))

Crossrefs

Cf. A000010, A000203.

Sequence in context: A093287 A231218 A186054 * A201154 A171344 A200533

Adjacent sequences: A082952 A082953 A082954 * A082956 A082957 A082958

Keyword

nonn

Author

Benoit Cloitre, May 26 2003

Extensions

More terms from Rick L. Shepherd, Jun 05 2003

Status

approved