A062784 Numbers k such that sigma(k) + phi(k) is a perfect square.

2, 4, 56, 110, 125, 161, 287, 391, 418, 423, 511, 588, 609, 675, 721, 799, 910, 935, 1048, 1057, 1102, 1130, 1281, 1351, 1457, 1485, 1630, 1716, 1799, 1826, 1921, 2047, 2060, 2177, 2255, 2378, 2403, 2449, 2457, 2472, 3199, 3266, 3915, 4010, 4376, 4417

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[4500], IntegerQ[Sqrt[DivisorSigma[1, #]+EulerPhi[#]]]&] (* Harvey P. Dale, Jan 18 2012 *)

Prog

(PARI) select(k->issquare(sigma(k) + eulerphi(k)), [1..5000])

Crossrefs

Cf. A065387.

Sequence in context: A084574 A358239 A087621 * A318642 A230884 A362735

Adjacent sequences: A062781 A062782 A062783 * A062785 A062786 A062787

Keyword

nonn

Author

Jason Earls, Jul 18 2001

Status

approved