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A110929
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The common value of sigma_2 for square-amicable numbers, sigma_2(m)=sigma_2(n), m<n.
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0
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50, 850, 1300, 2210, 6100, 8500, 14500, 18100, 22100, 22100, 22100, 24650, 26500, 32550, 42500, 42100, 48100, 48100, 48100, 68500, 68900, 84100, 92500, 103700, 110500, 110500, 110500, 140500, 158600, 174100, 201110, 186100, 221000, 224500
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| sigma_2(m)=sigma_2(n), m<n
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EXAMPLE
| sigma_2(30)=1^1+2^2+3^2+5^2+6^2+10^2+15^2+30^2=1300 and sigma_2(35)=1^2+5^2+7^2+35^2=1300.
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MAPLE
| with(numtheory); sigmap := proc(p, n) convert(map(proc(z) z^p end, divisors(n)), `+`) end; SA2:=[]: for z from 1 to 1 do for m to 1500 do M:=sigmap(2, m); for n from m+1 to 1500 do N:=sigmap(2, n); if N=M then SA2:=[op(SA2), [m, n, N]] fi od od od; SA2; select(proc(z) z[1]<=1000 end, SA2); #just to shorten it a bit
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CROSSREFS
| Cf. A001157, A002025, A002046, A063990.
Sequence in context: A160287 A104672 A086027 * A101929 A006360 A112890
Adjacent sequences: A110926 A110927 A110928 * A110930 A110931 A110932
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KEYWORD
| nonn
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AUTHOR
| Walter A. Kehowski (wkehowski(AT)cox.net), Sep 23 2005
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