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 A093553 #29 May 14 2023 23:48:09 %S A093553 2,3,13,12721,19441,5516281,5516281,7321991041,363500177041, %T A093553 2394196081201,3163427380990801,22755817971366481,3788978012188649281, %U A093553 2918756139031688155201 %N A093553 a(n) is the smallest number m such that (m+k-1)/k is prime for k=1,2,...,n. %C A093553 This sequence is A074200(n) + 1. See that entry for more information. - _N. J. A. Sloane_, May 04 2009 %C A093553 It is obvious that this sequence is increasing and each term is prime. If n > 3 then a(n) == 1 (mod 10). %C A093553 From _Jean-Christophe Hervé_, Sep 14 2014: (Start) %C A093553 a(n) == 1 (mod 120) for all n > 3 (see A163573). %C A093553 a(4) = 12721 is a quite remarkable number: it is a palindromic prime, its 5 (prime) digits sum to 13, still a prime number (and the preceding element in this sequence, among other things), and as the fourth element of this sequence, it is the smallest prime such that (p-1)/2, (p-2)/3 and (p-3)/4 are also prime, and many other properties. (End) %H A093553 Walter Nissen, <a href="http://upforthecount.com/math/pdor.html">Calculation without Words : Doric Columns of Primes</a>, Up for the Count ! %e A093553 a(9)=363500177041 because all the nine numbers 363500177041, %e A093553 (363500177041+1)/2, (363500177041+2)/3, (363500177041+3)/4, %e A093553 (363500177041+4)/5, (363500177041+5)/6, (363500177041+6)/7, %e A093553 (363500177041+7)/8 and (363500177041+8)/9 are primes and %e A093553 363500177041 is the smallest number m such that (m+k-1)/k is prime for k=1,2,...,9. %Y A093553 Cf. A072875. %K A093553 nonn,more %O A093553 1,1 %A A093553 _Farideh Firoozbakht_, Apr 14 2004