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 A373348 #7 Jul 26 2024 16:13:32 %S A373348 1,11,206,500015 %N A373348 Squarefree numbers k such that there exists a k-digit multiple of k that has k divisors. %C A373348 Squarefree numbers k such that A182749(k) and A182750(k) are nonzero. %C A373348 a(2) = 11 is the only prime term. %C A373348 Conjecture: a(3) = 206 = 2*103 and a(4) = 500015 = 5*100003 are the only semiprime terms. %e A373348 The table below lists the known terms k and, for each k, the corresponding multiple: %e A373348 . %e A373348 n a(n) = k k-digit multiple of k having k divisors %e A373348 - -------- ----------------------------------------- %e A373348 1 1 1 %e A373348 2 11 11^10 = 25937424601 %e A373348 3 206 2 * 103^102 = 4.0778...*10^205 %e A373348 4 500015 5^4 * 100003^100002 = 1.2553...*10^500014 %Y A373348 Cf. A182749, A182750. %K A373348 nonn,more %O A373348 1,2 %A A373348 _Jon E. Schoenfield_, Jun 01 2024