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 A156236 #9 Feb 16 2025 08:33:09 %S A156236 5,12,70,210,11310,145860,1560090,23130030,2491434660,200736225690, %T A156236 1906748513670,281993526895080,9427390580377770,904832960818356570, %U A156236 117584828859645537390,2928413909631253063020,400579656276180828206760 %N A156236 Smallest pentagonal number with n distinct prime factors. %C A156236 a(18) <= 44573764536301609937057730. - _Donovan Johnson_, Feb 15 2012 %H A156236 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PentagonalNumber.html">Pentagonal Numbers</a>. %e A156236 a(9) = 2491434660 = 2^2*3*5*11*13*17*19*29*31. 2491434660 is the smallest pentagonal number with 9 distinct prime factors. %Y A156236 Cf. A000326, A076551, A156237, A156238, A156239. %K A156236 nonn %O A156236 1,1 %A A156236 _Donovan Johnson_, Feb 07 2009 %E A156236 a(17) from _Donovan Johnson_, Jun 26 2011