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A067240 If n = Prod p_i^e_i, a(n) = Sum (p_i-1)*p_i^(e_i-1). 4
0, 1, 2, 2, 4, 3, 6, 4, 6, 5, 10, 4, 12, 7, 6, 8, 16, 7, 18, 6, 8, 11, 22, 6, 20, 13, 18, 8, 28, 7, 30, 16, 12, 17, 10, 8, 36, 19, 14, 8, 40, 9, 42, 12, 10, 23, 46, 10, 42, 21, 18, 14, 52, 19, 14, 10, 20, 29, 58, 8, 60, 31, 12, 32, 16, 13, 66, 18, 24, 11, 70, 10, 72, 37, 22, 20, 16, 15, 78, 12, 54, 41, 82, 10, 20, 43, 30, 14, 88, 11, 18, 24, 32, 47, 22, 18, 96, 43, 16, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

J. Kuzmanovich and A. Pavlichenkov, Finite groups of matrices whose entries are integers, Amer. Math. Monthly, 109 (2002), 173-186. (T on p. 181.)

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

For n > 1: a(n) = Sum phi(p_i^e_i). - T. D. Noe, Jul 10 2003

MAPLE

with(numtheory); A067240 := proc(n) local e, j; e := ifactors(n)[2]: add((e[j][1]-1)*e[j][1]^(e[j][2]-1), j=1..nops(e)); end;

MATHEMATICA

a[n_] := Total[ EulerPhi[ Power @@ #] & /@ FactorInteger[n]]; a[1] = 0; Table[a[n], {n, 1, 100}] (* Jean-Fran├žois Alcover, Jun 22 2012, after T. D. Noe *)

PROG

(Pari)

A067240(n)=

{

    local(f=factor(n), r=0, p, e);

    for (i=1, matsize(f)[1],

        p=f[i, 1];  e=f[i, 2];

        r += (p-1)*p^(e-1);

    );

    return(r);

} /* Joerg Arndt, Jun 10 2011 */

(Haskell)

a067240 1 = 0

a067240 n = sum $ map a000010 $ a141809_row $ toInteger n

-- Reinhard Zumkeller, Jun 13 2012

CROSSREFS

Cf. A000010, A141809.

Sequence in context: A113886 A220096 A122376 * A126080 A060681 A202479

Adjacent sequences:  A067237 A067238 A067239 * A067241 A067242 A067243

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mar 10 2002

STATUS

approved

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Last modified November 28 10:55 EST 2014. Contains 250323 sequences.