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 A175738 #16 Feb 16 2025 08:33:12 %S A175738 220,460,756,780,1140,1356,1496,2000,3050,3580,4532,4784,5220,7140, %T A175738 12132,20412,20650,22320,26076,39424,42392,65740,81252,87698,137104, %U A175738 164448,203506,370396,484140,491526,506940,667908,682820,777224,951114,1201538 %N A175738 Sizes of successive increasing gaps between 2-pseudoprimes. %C A175738 Rotkiewicz proves that a(n) < A175736(n)^2, and that the exponent can be replaced by 1 + epsilon for large enough n. %D A175738 A. Rotkiewicz, "Les intervalles contenants les nombres pseudopremiers", Rendiconti del Circolo Matematico di Palermo, Series 2, 14 (1965), pp. 278-280. %H A175738 Charles R Greathouse IV, <a href="/A175738/b175738.txt">Table of n, a(n) for n = 1..207</a> %H A175738 Charles R Greathouse IV, <a href="/A175738/a175738.png">Illustration of gap sizes vs. lower end</a> %H A175738 H. Halberstam and A. Rotkiewicz, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa13/aa13124.pdf">A gap theorem for pseudoprimes in arithmetic progression</a>, Acta Arithmetica 13 (1967/1968), pp. 395-404. %H A175738 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a> %H A175738 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %F A175738 a(n) = A175737(n) - A175736(n). %Y A175738 Cf. A001567 (2-pseudoprimes), A175736 (lower end), A175737 (upper end). %K A175738 nonn,nice %O A175738 1,1 %A A175738 _Charles R Greathouse IV_, Aug 28 2010