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 A343889 #20 May 06 2021 03:23:00 %S A343889 2,6,14,30,75,62,126,254,510,1022,2046,4094,8190,16382,32766,65534 %N A343889 Integer k of the pairs (k, m) ordered by m with 1 < k < m such that k has the same prime divisors as m, and, k+1 has the same prime divisors as m+1. %C A343889 First column of the array A343101. %C A343889 Even integer 2^q - 2, q >= 2 is a term (A000918), and only 75 is known to be not of this form. %H A343889 BxMO 2011, <a href="http://www.bxmo.org/problems/bxmo-problems-2011-fr.pdf">Third Benelux Mathematical Olympiad, Problème 1</a>. %H A343889 <a href="/index/O#Olympiads">Index to sequences related to Olympiads</a>. %e A343889 The corresponding pair to a(4) = 30 is (30, 960) because 30 = 2 * 3 * 5 and 960 = 2^5 * 3 * 5 while 961 = 31^2. %e A343889 The corresponding pair to a(5) = 75 is (75, 1215) because 75 = 3 * 5^2 and 1215 = 5 * 3^5, while 76 = 2^2 * 19 and 1216 = 2^6 * 19. %Y A343889 Cf. A000918, A087914 (2nd column), A343101 (array). %K A343889 nonn,hard,more %O A343889 1,1 %A A343889 _Bernard Schott_, May 03 2021