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A094468
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Numbers n such that sum of 9-th powers of divisors of n is divisible by the square of Euler-phi of n.
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1
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1, 2, 3, 6, 14, 42, 3810, 26670, 34162, 41256, 48546, 87096, 102486, 131934, 210482, 288792, 315723, 318990, 430122, 529848, 609672, 631446, 979830, 1023366, 1203960, 1473374, 1683126, 1920699, 2210061, 2241934, 2506086, 2549610
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| A013957[n]/A000010[n]^2 is integer.
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MATHEMATICA
| Select[Range[2600000], Divisible[Total[Divisors[#]^9], (EulerPhi[#])^2]&] (* From Harvey P. Dale, Mar 4 2011 *)
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PROG
| (PARI) for(n=1, 10000000, if(Mod(sigma(n, 9), eulerphi(n)^2)==0, print1(n, ", "))) (C. Ronaldo)
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CROSSREFS
| Cf. A015763, A000010, A091285, A013957.
Sequence in context: A098641 A188775 A056569 * A091285 A109459 A118986
Adjacent sequences: A094465 A094466 A094467 * A094469 A094470 A094471
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 19 2004
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EXTENSIONS
| More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 18 2005
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