cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A204822 Sum of divisors (A000203) of abundant numbers (A005101).

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%I A204822 #11 Feb 16 2025 08:33:16
%S A204822 28,39,42,60,72,91,90,96,124,120,120,168,144,144,195,168,186,224,180,
%T A204822 234,252,217,216,210,280,248,240,360,312,336,288,336,403,372,392,378,
%U A204822 363,480,360,372,546,384,508,399,468,465,504,434,576,600,504,456,504,560
%N A204822 Sum of divisors (A000203) of abundant numbers (A005101).
%H A204822 Harvey P. Dale, <a href="/A204822/b204822.txt">Table of n, a(n) for n = 1..1000</a>
%H A204822 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AbundantNumber.html">Abundant Number</a>
%F A204822 a(n) = A000203(A005101(n)) = A005101(n) + A205098(n).
%F A204822 a(n) << n log log n with lim sup a(n)/(n log log n) approximately 7.192. - _Charles R Greathouse IV_, Feb 19 2013
%t A204822 sdan[n_]:=Module[{ds=DivisorSigma[1,n]},If[ds>2n,ds,0]]; Select[ Array[ sdan, 300],#>0&] (* _Harvey P. Dale_, Aug 15 2015 *)
%o A204822 (PARI) for(n=6,200,s=sigma(n);if(s>2*n,print1(s", "))) \\ _Charles R Greathouse IV_, Feb 19 2013
%Y A204822 Cf. A204823 (sum of divisors of deficient numbers), A205098 (sum of proper divisors of abundant numbers).
%K A204822 nonn
%O A204822 1,1
%A A204822 _Jaroslav Krizek_, Jan 22 2012