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 A215805 #35 Jan 03 2022 21:10:14 %S A215805 5,7,13,19,29,31,43,53,61,67,71,179,239,263,269,293 %N A215805 Prime numbers p such that 10^p + 1 can be written in the form a^2 + 2*b^2. %C A215805 These numbers have no prime factors of the form 5 or 7 (mod 8) to an odd power. %H A215805 Samuel S. Wagstaff, Jr., The Cunningham Project, <a href="http://homes.cerias.purdue.edu/~ssw/cun/">Factorizations of 2^n-1, for odd n's < 1200.</a> %o A215805 (PARI) forprime(i=2, 100, a=factorint(10^i+1)~; has=0; for(j=1, #a, if(a[1, j]%8>4&&a[2, j]%2==1, has=1; break)); if(has==0&&i%2==1, print(i" -\t"a[1, ]))) %Y A215805 Cf. A000533, A001562, A062397, A215804. %K A215805 nonn %O A215805 1,1 %A A215805 _V. Raman_, Aug 23 2012 %E A215805 5 more terms from _V. Raman_, Aug 29 2012