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.
%I A222174 #15 May 13 2013 14:12:39 %S A222174 6,34,50,236,262,386,898,8362,26938,46594,80876,5244548,5462384, %T A222174 17062316,323987588,1162300834,1381439876 %N A222174 Numbers n such that sigma(n) + sigma(n-1) = 3n, where sigma(n) = sum of divisors of n (A000203). %C A222174 34 is the only number < 10^10 such that sigma(n) + sigma(n+1) = sigma(n) + sigma(n-1) = 3n (34 is a term of A067806). %C A222174 a(16) > 5*10^8. - _Giovanni Resta_, May 13 2013 %C A222174 a(18) > 10^10. - _Donovan Johnson_, May 13 2013 %t A222174 For[n=1, True, n++, If[DivisorSigma[1, n]+DivisorSigma[1, n-1]==3n, Print[n]]] %o A222174 (PARI) is(n)=sigma(n)+sigma(n-1)==3*n \\ _Charles R Greathouse IV_, May 13 2013 %Y A222174 Cf. A067806 (numbers n such that sigma(n) + sigma(n+1) = 3n), A000203. %K A222174 nonn %O A222174 1,1 %A A222174 _Jaroslav Krizek_, May 13 2013 %E A222174 a(12)-a(15) from _Giovanni Resta_, May 13 2013 %E A222174 a(16)-a(17) from _Donovan Johnson_, May 13 2013