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Search: id:A087004
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| A087004 |
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Numbers whose number of divisors equals the sum of their separate prime-power decompositions. |
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+0
2
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| 60, 120, 180, 504, 720, 11550, 12180, 17940, 19380, 21252, 22230, 26334, 27846, 29172, 32340, 34440, 34580, 43470, 48840, 56430, 59220, 59670, 63240, 66120, 70686, 82824, 85140, 91350, 95700, 95940, 99528, 112840, 113220, 113652, 115368
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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S. Kahan,"Divisor Advisory", Journal of Recreational Mathematics 30(1) 41-4 1999-2000 Baywood NY.
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EXAMPLE
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504=2^3*3^2*7 is in the sequence because d(504)=A000005(504)=(3+1)*(2+1)*(1+1)=24 = 2^3 + 3^2 + 7. Similarly for 32340=2^2*3*5*7^2*11, where d(32340) = 2^2 + 3 + 5 + 7^2 + 11 = 72.
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CROSSREFS
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Cf. A078511.
Sequence in context: A056866 A098136 A060793 this_sequence A049058 A056501 A056491
Adjacent sequences: A087001 A087002 A087003 this_sequence A087005 A087006 A087007
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KEYWORD
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nonn
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AUTHOR
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Lekraj Beedassy (blekraj(AT)yahoo.com), Oct 13 2003
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