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%I #8 Apr 08 2021 22:13:01
%S 1,2,4,9,13,16,18,25,36,37,49,50,61,64,73,81,97,100,101,109,113,121,
%T 137,144,157,169,173,181,193,225,229,241,242,256,257,277,281,289,313,
%U 317,324,325,333,337,353,361,373,397,400,401,409,421,433,441,457,484,512,529,541,549,576,577,578,601,613,617,625,641
%N Numbers k such that A003415(sigma(k)) < k.
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%t Select[Range[641], If[#2 < 2, 0, #2 Total[#2/#1 & @@@ FactorInteger[#2]]] < #1 & @@ {#, DivisorSigma[1, #]} &] (* _Michael De Vlieger_, Apr 08 2021 *)
%o (PARI)
%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o isA343216(n) = (A003415(sigma(n))<n);
%Y Cf. A000203, A003415.
%Y Cf. A343217 (complement).
%K nonn
%O 1,2
%A _Antti Karttunen_, Apr 08 2021
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