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 A326320 #16 Aug 23 2019 13:57:58 %S A326320 35803,36349,41299,43591,45109,45583,53821 %N A326320 Numbers that cannot be written as a difference of 13-smooth numbers. %C A326320 Terms were found by generating in ascending order the 13-smooth numbers up to some limit and checking the differences. The first 7 candidates k have been proved true by showing a set of 31 congruences to be impossible (see link below). For a discussion iof this method of proof see A308247. %H A326320 Esteban Crespi de Valldaura, <a href="/A326320/a326320.txt">Congruences needed in proof of a(1)..a(7)</a> %e A326320 35803 = A308247(6) cannot be written as the difference of 13-smooth numbers. All smaller numbers can; for example, 9007 = 3^2*7*11*13 - 2, 10091 = 2^2*3*5*13^2 - 7^2. %Y A326320 Cf. A080197 (13-smooth numbers). %Y A326320 Cf. numbers not the difference of p-smooth numbers for other values of p: A101082 (p=2), A290365 (p=3), A308456 (p=5), A326318 (p=7), A326319 (p=11). %Y A326320 Cf. A308247. %K A326320 nonn,more %O A326320 1,1 %A A326320 _Esteban Crespi de Valldaura_, Jun 26 2019