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.

A283418 Numbers n such that n and n+1 are primitive abundant.

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%I A283418 #24 Jun 29 2019 10:19:25
%S A283418 82004,158235,326864,442035,516704,1102724,1606275,2151435,2697435,
%T A283418 2912084,2921535,2979675,3002804,3241755,3647475,4322835,5801984,
%U A283418 5905844,6069195,7251075,7387604,7553924,8272124,8788724,9292724,9909584
%N A283418 Numbers n such that n and n+1 are primitive abundant.
%C A283418 Intersection of A091191 and -1 + A091191.
%H A283418 Amiram Eldar, <a href="/A283418/b283418.txt">Table of n, a(n) for n = 1..1000</a>
%e A283418 82004 is in the sequence because it is abundant (sum divisors = 164640, > 2*82004) and 82005 is also abundant (sum divisors = 165888, > 2*82005).
%t A283418 fQ[m_] := DivisorSigma[1, m] > 2 m;
%t A283418 gQ[m_] := fQ[m] && Union[fQ /@ Rest[Most[Divisors[m]]]] == {False};
%t A283418 V = Select[Range[10^7], gQ]; Intersection[V, V - 1]
%Y A283418 Cf. A091191, A005105, A096399.
%K A283418 nonn
%O A283418 1,1
%A A283418 _Emmanuel Vantieghem_, May 02 2017