A061884 a(n) = Sum_{ d | n } phi(lcm(d,n/d)), where phi(n) = Euler totient A000010.

1, 2, 4, 5, 8, 8, 12, 12, 14, 16, 20, 20, 24, 24, 32, 26, 32, 28, 36, 40, 48, 40, 44, 48, 44, 48, 48, 60, 56, 64, 60, 56, 80, 64, 96, 70, 72, 72, 96, 96, 80, 96, 84, 100, 112, 88, 92, 104, 90, 88, 128, 120, 104, 96, 160, 144, 144, 112, 116, 160, 120, 120, 168, 116, 192

Offset

1,2

Links

Table of n, a(n) for n=1..65.

Maple

A061884 := proc(n) local b, d: b := 0; for d from 1 to n do if irem(n, d)=0 then b := b+phi(lcm(d, n/d)); fi; od; RETURN(b); end:

Mathematica

Table[Plus @@ Map[ EulerPhi[LCM[ #, n/# ]] &, Select[ Range@n, (Mod[n, # ] == 0) &]], {n, 65}] (* Robert G. Wilson v, Sep 30 2006 *)

Prog

(PARI) a(n)=sumdiv(n, d, eulerphi(lcm(d, n/d))) \\ Charles R Greathouse IV, Feb 21 2013

Crossrefs

Cf. A000010, A001616, A057670, A007427.

Sequence in context: A331376 A369601 A345426 * A286002 A029935 A317625

Adjacent sequences: A061881 A061882 A061883 * A061885 A061886 A061887

Keyword

easy,nonn

Author

Vladeta Jovovic, May 12 2001

Status

approved