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 A107291 #18 Sep 22 2024 02:06:53 %S A107291 8,33,41,495,657,1904,4497,9369,11096,11465,12542,20819 %N A107291 Numbers k such that 10^k*(10^7*(-1+10^k)+6083806) + 10^k - 1 is prime. %C A107291 These are palprimes with curved digits, i.e., palindromic primes composed of only 0's, 3s, 6s, 8s, or 9s and they have all been proved prime. No more terms up to 7000. Primality proof for the largest: PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 [N+1, Brillhart-Lehmer-Selfridge] Running N+1 test using discriminant 3, base 1+sqrt(3) Running N+1 test using discriminant 3, base 3+sqrt(3) Running N+1 test using discriminant 3, base 5+sqrt(3) 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 is prime! (147.0046s+0.0074s) %H A107291 R. Ondrejka, <a href="http://www.utm.edu/research/primes/lists/top_ten/">The Top Ten: a Catalogue of Primal Configurations</a>. %e A107291 8 is a term because 10^8*(10^7*(-1+10^8)+6083806)+10^8-1 = 99999999608380699999999 is prime. %o A107291 (PARI) is(n)=ispseudoprime(10^n*(10^7*(-1+10^n)+6083806)+10^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A107291 Cf. A079652. %K A107291 base,nonn,more %O A107291 1,1 %A A107291 _Jason Earls_, May 20 2005 %E A107291 a(8)-a(12) from _Michael S. Branicky_, Sep 21 2024