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A046756
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d(n)^4 divides n.
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4
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1, 625, 6561, 117649, 4100625, 31250000, 37515625, 73530625, 771895089, 1000000000, 2147483648, 6442450944, 10737418240, 15032385536, 23622320128, 25937424601, 27917287424, 32212254720, 33059881728, 36507222016, 40802189312, 45097156608, 49392123904
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Proper subset of A033950, A046754 and A046755. Relatively prime terms are in the sequence together with their products like 73530625 or 771895089000000000.
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EXAMPLE
| If n=625, d(n)=Sigma[ 0,n ]=5. Its 4th power is 625 which divides n.
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MATHEMATICA
| Select[ Range[ 1, 14500000 ], IntegerQ[ #/(DivisorSigma[ 0, # ])^2 ]& ]
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CROSSREFS
| Cf. A033950, A046754, A046755.
Sequence in context: A171995 A046755 A016816 * A143026 A064781 A055868
Adjacent sequences: A046753 A046754 A046755 * A046757 A046758 A046759
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu)
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EXTENSIONS
| a(6)-a(20) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 30 2008
a(21)-a(23) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 08 2011
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