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 A211660 #10 Feb 11 2020 03:54:23 %S A211660 1,2,3,5,7,27,43,98,146,169,171,197,200,217,241,257,281,331,347,379, %T A211660 386,409,448,461,487,505,507,509,547,554,576,577,641,800,821,829,841, %U A211660 857,907,937,1117,1250,1261,1283,1289,1322,1352,1359,1387,1415,1601,1621 %N A211660 Numbers k such that k and k+2 both have unique values of sigma(k) and sigma(k+2); sigma(k) = A000203(k) = sum of divisors of k. %C A211660 Subsequence of A211656. Number k is in sequence iff k and k+2 are in A211656. %C A211660 Supersequence of A211767 (lesser of twin primes p, p+2 with unique values of sigma(p) and sigma(p+2)). %H A211660 Amiram Eldar, <a href="/A211660/b211660.txt">Table of n, a(n) for n = 1..10000</a> %e A211660 Number 27 is in sequence because sigma(27) = 40, sigma(29) = 30 and there are no other numbers m, n with sigma(m) = 40 or sigma(n) = 30. %Y A211660 Cf. A000203, A211656, A211657, A211658, A211659, A211767, A211768, A211769. %K A211660 nonn %O A211660 1,2 %A A211660 _Jaroslav Krizek_, Apr 20 2012