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A067240
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If n = Prod p_i^e_i, a(n) = Sum (p_i-1)*p_i^(e_i-1).
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4
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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; internal format)
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OFFSET
| 1,3
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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.)
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FORMULA
| a(n) = Sum phi(p_i^e_i). - T. D. Noe (noe(AT)sspectra.com), Jul 10 2003
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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;
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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 */
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CROSSREFS
| Sequence in context: A113885 A113886 A122376 * A126080 A060681 A202479
Adjacent sequences: A067237 A067238 A067239 * A067241 A067242 A067243
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mar 10 2002
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