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 A213019 #19 Apr 03 2023 10:36:13 %S A213019 9,95,959,9599,95999,959999,9599999,95999987,959999879,9599998799, %T A213019 95999987999,959999879999,9599998791827,95999987918279, %U A213019 959999879182793,9599998791715333,95999987917153339,959999879171533399,9599998791715333999,95999987917153339993 %N A213019 Largest n-digit right-truncatable semiprime. %C A213019 For the definition of a right-truncatable semiprime, see A213017. The largest possible right-truncatable semiprime a(38) = A085733(56076) = 95861957783594714393831931415189937897, found by S.S. Gupta, is the last term of this sequence. %H A213019 Hugo Pfoertner, <a href="/A213019/b213019.txt">Table of n, a(n) for n = 1..38</a> (all terms) %H A213019 Shyam Sunder Gupta, <a href="https://t5k.org/curios/page.php?curio_id=6861">The largest right-truncatable semiprime</a>, Prime Curios. %e A213019 a(1) = 9 = 3*3 %e A213019 a(2) = 95 = 5*19 and none of 96, 97, 98, 99 semiprime %e A213019 a(3) = 959 = 7*137 %e A213019 a(4) = 9599 = 29*331 %e A213019 a(5) = 95999 = 17*5647 %e A213019 a(6) = 959999 = 643*1493 %e A213019 a(7) = 9599999 = 1019*9421 %e A213019 a(8) = 95999987 = 7349*13063, 9599998 = 2*4799999 and none of 95999988 ... 95999999 semiprime %Y A213019 Cf. A001358, A085733, A213017, A213018. %K A213019 nonn,base,fini,full %O A213019 1,1 %A A213019 _Hugo Pfoertner_, Jun 27 2012