cp's OEIS Frontend

A348698 Integers m such that sigma(m) + sigma(m+1) + sigma(m+2) - sigma(m+3) <= 0, where sigma is the sum of divisors.

%I A348698 #15 Nov 11 2021 11:24:59
%S A348698 10077,15117,20157,25197,27717,37797,41577,42837,45357,50397,55437,
%T A348698 65517,69297,70557,75597,81897,83157,85677,90717,92397,98277,100797,
%U A348698 102957,105837,110877,120117,120957,124737,125997,128517,131037,136077,138597,142797,147417,147837
%N A348698 Integers m such that sigma(m) + sigma(m+1) + sigma(m+2) - sigma(m+3) <= 0, where sigma is the sum of divisors.
%C A348698 Integers m such that A348688(m) <= 0.
%C A348698 At this time, only 2 integers are known with A348688(x)=0: 591357 and 735205677.
%C A348698 The least term not == 7 (mod 10) is 3027021.
%H A348698 Michel Marcus, <a href="/A348698/b348698.txt">Table of n, a(n) for n = 1..3269</a>
%t A348698 s = DivisorSigma[1, Range[1.5*10^5]]; Position[s[[1 ;; -4]] + s[[2 ;; -3]] + s[[3 ;; -2]] - s[[4 ;; -1]], _?(# <= 0 &)] // Flatten (* _Amiram Eldar_, Oct 30 2021 *)
%o A348698 (PARI) isok(m) = sigma(m) + sigma(m+1) + sigma(m+2) - sigma(m+3) <= 0;
%Y A348698 Cf. A000203, A348688.
%K A348698 nonn
%O A348698 1,1
%A A348698 _Michel Marcus_, Oct 30 2021