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 A211659 #9 Feb 11 2020 03:54:19 %S A211659 1,2,3,4,7,8,12,18,36,49,72,100,128,133,148,162,192,199,217,218,256, %T A211659 288,313,337,400,421,457,511,547,548,562,576,577,578,652,661,676,721, %U A211659 841,842,871,876,1058,1093,1152,1171,1191,1200,1227,1233,1249,1282,1306 %N A211659 Numbers k such that k and k+1 both have unique values of sigma(k) and sigma(k+1); sigma(k) = A000203(k) = sum of divisors of k. %C A211659 Subsequence of A211656. Number k is in sequence iff k and k+1 are in A211656. %H A211659 Amiram Eldar, <a href="/A211659/b211659.txt">Table of n, a(n) for n = 1..10000</a> %e A211659 Number 36 is in sequence because sigma(36) = 91, sigma(37) = 38 and there are no other numbers m, n with sigma(m) = 91 or sigma(n) = 38. %Y A211659 Cf. A000203, A211656, A211657, A211658, A211660. %K A211659 nonn %O A211659 1,2 %A A211659 _Jaroslav Krizek_, Apr 20 2012