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.

A246852 Numbers n such that sigma(n+2) - sigma(n) = n + 2.

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%I A246852 #40 Jul 23 2024 21:14:54
%S A246852 1,2,22,14926,31048,69106,246262,5860168,307164670,881198662,
%T A246852 1489455646,2386555630,8225563702,14311679062,111494234182,
%U A246852 154357775302,299004519622,870455062822,970388922262,991817878342,1677028870822,1782783762502,1830446935222
%N A246852 Numbers n such that sigma(n+2) - sigma(n) = n + 2.
%C A246852 Also numbers n such that A001065(n+2) = A000203(n). - _Michel Marcus_, Sep 06 2014
%H A246852 Giovanni Resta, <a href="/A246852/b246852.txt">Table of n, a(n) for n = 1..33</a> (terms < 10^13)
%e A246852 Number 22 is in sequence because sigma(22+2) - sigma(22) = 60 - 36 = 24 = 22 + 2.
%t A246852 Select[Range[6*10^6], DivisorSigma[1, # + 2] - DivisorSigma[1, #] == # + 2 &] (* _Jake L Lande_, Jun 30 2024 *)
%o A246852 (Magma) [n:n in[1..10^7] | SumOfDivisors(n+2)-SumOfDivisors(n) eq n+2]
%o A246852 (PARI)
%o A246852 for(n=1,10^7,if(sigma(n+2)-sigma(n)==n+2,print1(n,", "))) \\ _Derek Orr_, Sep 05 2014
%Y A246852 Cf. A000203, A067816, A246851, A246853, A246854, A246855.
%K A246852 nonn
%O A246852 1,2
%A A246852 _Jaroslav Krizek_, Sep 05 2014
%E A246852 a(9)-a(14) from _Hiroaki Yamanouchi_, Sep 10 2014
%E A246852 a(15)-a(23) from _Giovanni Resta_, Jul 13 2015