A068366 Numbers k such that phi(sigma(k)+k) = sigma(k).

1, 7, 15, 127, 267, 315, 495, 621, 969, 1155, 1917, 5649, 7515, 12267, 14911, 17271, 22347, 26265, 28671, 30549, 31641, 32895, 45195, 48093, 56697, 60801, 64923, 77409, 79827, 82731, 83559, 116745, 123387, 172653, 173901, 179223, 184869

Offset

1,2

Comments

Are there any even values in the sequence?

Links

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

Mathematica

q[n_] := Module[{s = DivisorSigma[1, n]}, EulerPhi[s + n] == s]; Select[Range[10^5], q] (* Amiram Eldar, Dec 11 2023 *)

Prog

(PARI) for(n=1, 300000, if(eulerphi(sigma(n)+n)==sigma(n), print1(n, ", ")))

Crossrefs

Cf. A000010, A000203.

Sequence in context: A032004 A032018 A243470 * A156499 A137881 A042725

Adjacent sequences: A068363 A068364 A068365 * A068367 A068368 A068369

Keyword

easy,nonn

Author

Benoit Cloitre, Feb 28 2002

Extensions

More terms from Rick L. Shepherd, Apr 22 2002

Status

approved