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 A124144 Perfect powers pp such that sigma(n)=pp for some abundant number n. 0
 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; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE a(1)=144 since sigma(66)=144>2*66=132. MAPLE 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; CROSSREFS Cf. A001597, A005101, A065496. Sequence in context: A165078 A135780 A069701 * A276564 A061040 A159456 Adjacent sequences:  A124141 A124142 A124143 * A124145 A124146 A124147 KEYWORD nonn AUTHOR Walter Kehowski, Dec 01 2006 STATUS approved

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Last modified January 24 01:05 EST 2020. Contains 331178 sequences. (Running on oeis4.)