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.

A333950 Odd recursive abundant numbers: odd numbers k such that A333926(k) > 2*k.

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%I A333950 #7 Apr 12 2020 09:50:59
%S A333950 1575,2205,3465,4095,5355,5775,5985,6435,6825,7245,8085,8415,8925,
%T A333950 9135,9555,9765,11025,11655,12705,12915,13545,14805,15015,16695,17325,
%U A333950 18585,19215,19635,20475,21105,21945,22365,22995,23205,24255,24885,25935,26145,26565,26775
%N A333950 Odd recursive abundant numbers: odd numbers k such that A333926(k) > 2*k.
%H A333950 Amiram Eldar, <a href="/A333950/b333950.txt">Table of n, a(n) for n = 1..10000</a>
%e A333950 1575 is a term since it is odd and A333926(1575) = 3224 > 2 * 1575.
%t A333950 recDivQ[n_, 1] = True; recDivQ[n_, d_] := recDivQ[n, d] = Divisible[n, d] && AllTrue[FactorInteger[d], recDivQ[IntegerExponent[n, First[#]], Last[#]] &]; recDivs[n_] := Select[Divisors[n], recDivQ[n, #] &]; f[p_, e_] := 1 + Total[p^recDivs[e]]; recDivSum[1] = 1; recDivSum[n_] := Times @@ (f @@@ FactorInteger[n]); Select[2*Range[15000] + 1, recDivSum[#] > 2*# &]
%Y A333950 Intersection of A005408 and A333928.
%Y A333950 Cf. A333926.
%Y A333950 Analogous sequences: A005231, A094889 (nonunitary), A129485 (unitary), A127666 (infinitary), A293186 (bi-unitary), A321147 (exponential).
%K A333950 nonn
%O A333950 1,1
%A A333950 _Amiram Eldar_, Apr 11 2020