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A063735 Square deficient numbers. 2

%I

%S 1,4,9,16,25,49,64,81,121,169,225,256,289,361,441,484,529,625,676,729,

%T 841,961,1024,1089,1156,1225,1369,1444,1521,1681,1849,2025,2116,2209,

%U 2401,2601,2809,3025,3249,3364,3481,3721,3844,3969,4096,4225,4489,4761

%N Square deficient numbers.

%H Harry J. Smith, <a href="/A063735/b063735.txt">Table of n, a(n) for n=1..1000</a>

%t Select[#^2 & /@ Range[70], DivisorSigma[1, #] < 2 # &]

%o (PARI) j=[]; for(n=1,8000, if(sigma(n)<(2*n),a=n; if(issquare(a),j=concat(j,a)))); j

%o (PARI) { n=0; for (m=1, 10^9, if (issquare(m) && sigma(m)<(2*m), write("b063735.txt", n++, " ", m); if (n==1000, break)) ) } \\ _Harry J. Smith_, Aug 29 2009

%o (PARI) { n=0; for (m=1, 10^9, s=m^2; if (sigma(s)<(2*s), write("b063735.txt", n++, " ", s); if (n==1000, break)) ) } \\ _Harry J. Smith_, Aug 29 2009]

%Y Intersection of A000290 and A005100.

%K nonn

%O 1,2

%A _Jason Earls_, Aug 13 2001

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Last modified May 27 12:27 EDT 2020. Contains 334657 sequences. (Running on oeis4.)