Search: id:A065496
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%I A065496
%S A065496 3,7,21,22,31,66,70,81,93,94,102,110,115,119,127,142,159,170,187,210,
%T A065496 214,217,265,282,310,322,343,345,357,364,381,382,385,400,472,497,510,
%U A065496 517,527,642,651,679,690,710,714,742,745,770,782,795,820,862,884,889
%N A065496 Numbers n such that sigma(n) is a nontrivial power, i.e. sigma(n) = a^b 
               where a and b are greater than 1.
%C A065496 Probably an unsolved problem: what numbers can appear as bases in the 
               representations of sigma(n) as nontrivial powers?
%e A065496 sigma(21) = 2^5, sigma(22) = 6^2, sigma(94) = 12^2.
%t A065496 Do[s = DivisorSigma[1, n]; If[ Position[ Union[ Transpose[ FactorInteger[s]] 
               [[2]]], 1] != {{1}} && Union[ Mod[ Union[ Transpose[ FactorInteger[s]] 
               [[2]]], Union[ Transpose[ FactorInteger[s]] [[2]]] [[1]]]] == {0}, 
               Print[n]], {n, 2, 10^3} ] - Robert G. Wilson v Nov 26 2001
%Y A065496 Cf. A000203, A046528.
%Y A065496 Sequence in context: A024331 A007174 A091184 this_sequence A018479 A090504 
               A018548
%Y A065496 Adjacent sequences: A065493 A065494 A065495 this_sequence A065497 A065498 
               A065499
%K A065496 nonn
%O A065496 1,1
%A A065496 Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Nov 24 2001
%E A065496 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 25 2001

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