A063935 q(n) = sigma(n) - n, where q(n) = n + e(n) + e(n-e(n)) and e(n) = n - eulerphi(n).

300, 72504, 157344, 1470456, 3454944, 7438656, 8583168, 10097920, 32175072, 1519507968, 1699447296, 8450553312

Offset

1,1

Links

Table of n, a(n) for n=1..12.

Mathematica

F[n_] := Abs[EulerPhi[n] - n]; Q[n_] := n+F[n]+F[n-F[n]]; Do[If[Q[n] == DivisorSigma[1, n] - n, Print[n]], {n, 10^9}] (* Ryan Propper, Jan 01 2007 *)

Prog

(PARI) e(n) = n - eulerphi(n);
q(n) = n+e(n)+e(n-e(n));
for(n=1, 10^8, if(q(n)==sigma(n)-n, print1(n, ", ")))

Crossrefs

Cf. A051953 (n - eulerphi(n)).

Sequence in context: A036517 A223350 A190880 * A294687 A015275 A051306

Adjacent sequences: A063932 A063933 A063934 * A063936 A063937 A063938

Keyword

more,nonn

Author

Jason Earls, Aug 31 2001

Extensions

One more term from Ryan Propper, Jan 01 2007

a(10)-a(12) from Lars Blomberg, Oct 27 2015

Offset corrected by Altug Alkan, Oct 31 2015

Status

approved