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 A279623 #25 Sep 08 2022 08:46:18 %S A279623 1,1,2,5,3,2,7,877,2,3,5,2,37,27644437,2,5,241,2,7,271,2,3,3,2,3,13,2, %T A279623 47,5,2,3,11,2,5694673,3,2,29,3,2,6353,3221,2, %U A279623 35742549198872617291353508656626642567,3,2,5,5,2,3,7615441337805454611187,2 %N A279623 a(n) = smallest prime factor of n-th Bell number, or 1 if there are none. %H A279623 Amiram Eldar, <a href="/A279623/b279623.txt">Table of n, a(n) for n = 0..131</a> (terms 0..100 from Robert G. Wilson v) %F A279623 a(n) = A020639(A000110(n)). - _Robert Israel_, Dec 25 2016 %t A279623 f[n_] := (FactorInteger@ BellB@ n)[[1, 1]]; Array[f, 50, 0] %o A279623 (Magma) [1,1] cat [Minimum(PrimeDivisors(Bell(n))): n in [2..50]]; %Y A279623 Cf. A000110, A020639, A139044, A144293. %K A279623 nonn %O A279623 0,3 %A A279623 _Vincenzo Librandi_, Dec 25 2016