Search: id:A006532
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%I A006532 M3089
%S A006532 1,3,22,66,70,81,94,115,119,170,210,214,217,265,282,310,322,343,345,
%T A006532 357,364,382,385,400,472,497,510,517,527,642,651,679,710,742,745,782,
%U A006532 795,820,862,884,889,930,935,966,970,1004,1029,1066,1080,1092,1146
%N A006532 Numbers n such that sum of divisors is a square.
%C A006532 If a and b are in the sequence and relatively prime, then a*b is also 
               in the sequence. [From Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), 
               Jan 12 2009]
%D A006532 A. H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1964, 
               p. 8.
%D A006532 J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 94, p. 33, Ellipses, 
               Paris 2008.
%D A006532 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006532 D. Wells, Curious and interesting numbers, Penguin Books, p. 111.
%H A006532 T. D. Noe, <a href="b006532.txt">Table of n, a(n) for n=1..10000</a>
%H A006532 <a href="Sindx_Su.html#ssq">Index entries for sequences related to sums 
               of squares</a>
%p A006532 for i from 1 to 1000 do if issqr(sigma(i)) then print(i); fi; od;
%t A006532 Select[ Range[ 1150 ], IntegerQ[ Sqrt[ DivisorSigma[ 1, # ] ] ]& ]
%Y A006532 Cf. A074385, A000203. [From Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), 
               Jan 12 2009]
%Y A006532 Sequence in context: A041103 A104604 A139272 this_sequence A005288 A143166 
               A055550
%Y A006532 Adjacent sequences: A006529 A006530 A006531 this_sequence A006533 A006534 
               A006535
%K A006532 easy,nonn,nice
%O A006532 1,2
%A A006532 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A006532 Additional reference from Felice Russo (felice.russo(AT)katamail.com). 
               More terms from Enoch Haga (Enokh(AT)comcast.net).

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