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 A100857 #23 Jul 26 2025 08:04:31 %S A100857 3,5,29,727,3628811,6599,6385271,1291883,315389197,123662437024088191, %T A100857 2107707330310062524424576119,50717732086848522419, %U A100857 14602944428087660261,55353784249983832172137,16166897314580017 %N A100857 a(n) = greatest prime factor of (prime(n) - 1)! + prime(n). %H A100857 Amiram Eldar, <a href="/A100857/b100857.txt">Table of n, a(n) for n = 1..28</a> (using factordb.com) %H A100857 Dario A. Alpern, <a href="https://www.alpertron.com.ar/ECM.HTM">Factorization using the Elliptic Curve Method</a>. %H A100857 FactorDB, <a href="http://factordb.com/index.php?query=109%2B108%21">Status of 109+108!</a>. %F A100857 a(n) = A006530(A100856(n)). %F A100857 a(n) > A000040(n). %e A100857 n=6: (prime(6)-1)! + prime(6) = 12! + 13 = 479001600 + 13 = 479001613 = 29*2503*6599, therefore a(6) = 6599. %t A100857 FactorInteger[(#-1)!+#][[-1,1]]&/@Prime[Range[15]] (* _Harvey P. Dale_, Jul 23 2011 *) %Y A100857 Cf. A006530, A100856, A100858. %K A100857 nonn %O A100857 1,1 %A A100857 _Reinhard Zumkeller_, Nov 20 2004