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A061884 a(n) = sum_{ d | n } phi(lcm(d,n/d)), where phi(n) = Euler totient A000010. 4
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 (list; graph; refs; listen; history; text; internal format)
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. A001616, A057670, A007427.

Sequence in context: A085624 A331376 A345426 * A286002 A029935 A317625

Adjacent sequences:  A061881 A061882 A061883 * A061885 A061886 A061887

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, May 12 2001

STATUS

approved

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Last modified September 27 06:54 EDT 2021. Contains 347673 sequences. (Running on oeis4.)