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Search: id:A124144
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| A124144 |
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Perfect powers pp such that sigma(n)=pp for some abundant number n. |
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+0
1
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| 144, 216, 576, 784, 961, 1296, 1728, 1764, 2304, 2744, 3136, 3600, 3844, 4356, 5184, 6084, 7056, 7776, 8100, 9216, 11664, 12544, 13824, 14400, 15376, 15876, 17424, 19600, 20736, 21952, 24336, 28224
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1)=144 since sigma(66)=144>2*66=132.
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MAPLE
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with(numtheory); egcd := proc(n::posint) local L; if n>1 then L:=ifactors(n)[2]; L:=map(z->z[2], L); return igcd(op(L)) else return 1 fi; end; L:=[]: P:={}: for w to 1 do for n from 1 to 10000 do s:=sigma(n); if s>2*n and egcd(s)>1 then print(n, s, ifactor(s)); L:=[op(L), n]; P:=P union {s}; fi od od; L; P;
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CROSSREFS
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Cf. A001597, A005101, A065496.
Sequence in context: A064021 A135780 A069701 this_sequence A061040 A064563 A008436
Adjacent sequences: A124141 A124142 A124143 this_sequence A124145 A124146 A124147
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KEYWORD
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nonn
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AUTHOR
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Walter A. Kehowski (wkehowski(AT)cox.net), Dec 01 2006
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