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 A064079 #15 Sep 26 2018 03:03:12 %S A064079 2,1,13,5,121,7,1093,41,757,61,88573,73,797161,547,4561,3281,64570081, %T A064079 703,581130733,1181,368089,44287,47071589413,6481,3501192601,398581, %U A064079 387440173,478297,34315188682441,8401,308836698141973,21523361 %N A064079 Zsigmondy numbers for a = 3, b = 1: Zs(n, 3, 1) is the greatest divisor of 3^n - 1^n (A024023) that is relatively prime to 3^m - 1^m for all positive integers m < n. %C A064079 By Zsigmondy's theorem, the n-th Zsigmondy number for bases a and b is not 1 except in the three cases (1) a = 2, b = 1, n = 1, (2) a = 2, b = 1, n = 6, (3) n = 2 and a+b is a power of 2. %H A064079 K. Zsigmondy, <a href="http://dx.doi.org/10.1007/BF01692444">Zur Theorie der Potenzreste</a>, Monatsh. f. Math. 3 (1892) 265-284. %Y A064079 Cf. A024023, A064078, A064080, A064081, A064082, A064083. %K A064079 nonn %O A064079 1,1 %A A064079 _Jens Voß_, Sep 04 2001 %E A064079 More terms from _Vladeta Jovovic_, Sep 06 2001 %E A064079 Definition corrected by _Jerry Metzger_, Nov 04 2009