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%I #6 Aug 26 2020 20:44:37
%S 1,2,4,9,16,18,25,36,50,64,100,144,225,256,289,400,450,576,578,729,
%T 784,900,1024,1156,1296,1458,1600,1681,1764,1800,1936,2304,2401,2601,
%U 2704,2916,3136,3362,3481,3600,4096,4356,4624,4802,4900,5041,5184,5202,5328,5776,5832,6084,6400,6561,6724,6962,7056,7225,7744,7921,8192
%N Numbers k such that A064989(sigma(k)) >= k.
%C Not all terms are squares or twice squares: the first terms not in A028982 are: 5328, 8784, 22608, 27792, 35136, 39888, 45072, 57168, 58320, 60624, ...
%o (PARI)
%o A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
%o isA337343(n) = (A064989(sigma(n))>=n);
%Y Cf. A000203, A028982, A064989, A337344 (odd terms).
%K nonn
%O 1,2
%A _Antti Karttunen_, Aug 26 2020
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