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A046756 d(n)^4 divides n. +0
4
1, 625, 6561, 117649, 4100625, 31250000, 37515625, 73530625, 771895089, 1000000000, 2147483648, 6442450944, 10737418240, 15032385536, 23622320128, 25937424601, 27917287424, 32212254720, 33059881728, 36507222016 (list; graph; listen)
OFFSET

1,2

EXAMPLE

If n=625, d(n)=Sigma[ 0,n ]=5. Its 4th power is 625 which divides n.

MATHEMATICA

Select[ Range[ 1, 14500000 ], IntegerQ[ #/(DivisorSigma[ 0, # ])^2 ]& ]

CROSSREFS

Proper subset of A033950, A046754 and A046755. Relatively prime terms are in the sequence thogether with their products like 73530625 or 771895089000000000.

Cf. A033950.

Sequence in context: A043352 A046755 A016816 this_sequence A143026 A064781 A055868

Adjacent sequences: A046753 A046754 A046755 this_sequence A046757 A046758 A046759

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu)

EXTENSIONS

a(6)-a(20) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 30 2008

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Last modified December 9 14:43 EST 2009. Contains 170430 sequences.


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