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 A309582 #43 Sep 07 2024 08:00:23 %S A309582 0,10,118,138,1143,16344,19324 %N A309582 Numbers k such that 36*10^(2*k) + 6*10^k + 1 is prime. %C A309582 a(6) > 6000. - _Tyler NeSmith_, Dec 05 2021 %e A309582 43 is prime ==> a(1) = 0. %e A309582 3661 = 7 * 523. %e A309582 360601 = 19 * 18979. %e A309582 36006001 = 67 * 537403. %e A309582 3600060001 = 457 * 7877593. %e A309582 360000600001 = 7 * 51428657143. %e A309582 36000006000001 = 379 * 94986823219. %e A309582 3600000060000001 = 7 * 43 * 64609 * 185115589. %e A309582 360000000600000001 = 19 * 18947368452631579. %e A309582 36000000006000000001 = 307 * 1249 * 1071121 * 87652267. %e A309582 3600000000060000000001 is prime ==> a(2) = 10. %o A309582 (PARI) for(k=0, 1e3, if(ispseudoprime(36*100^k+6*10^k+1), print1(k", "))) %Y A309582 Cf. A309738. %K A309582 nonn,more,base %O A309582 1,2 %A A309582 _Seiichi Manyama_, Aug 15 2019 %E A309582 a(6) from _Michael S. Branicky_, Apr 24 2023 %E A309582 a(7) from _Michael S. Branicky_, Sep 07 2024