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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

Table of n, a(n) for n=1..32.

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 November 19 19:18 EST 2019. Contains 329323 sequences. (Running on oeis4.)