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 A087175 #16 Feb 16 2025 08:32:51
%S A087175 0,1,1,1,1,1,2,2,3,3,2,2,1,2,2,3,2,3,3,3,3,3,2,3,3,4,4,3,3,3,3,3,3,3,
%T A087175 3,1,3,3,4,4,4,3,3,3,3,4,4,3,3,3,3,5,3,5,4,3,3,4,5,3,5,4,3,5,2,4,2,4,
%U A087175 3,4,3,3,3,4,6,2,1,4,4,4,2,4,3,5,2,5,2,4,3,2,3,2,2,6,2,4,7,3,2,5,3,3
%N A087175 Number of distinct primes dividing the n-th partition number.
%H A087175 Giovanni Resta, <a href="/A087175/b087175.txt">Table of n, a(n) for n = 1..10000</a>
%H A087175 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DistinctPrimeFactors.html">Distinct Prime Factors</a>
%H A087175 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PartitionFunction.html">Partition Function</a>
%H A087175 Wikipedia, <a href="http://en.wikipedia.org/wiki/Partition_(number_theory)">Partition function</a>
%F A087175 a(n) = A001221(A000041(n)).
%e A087175 A000041(14) = 135 = 3^3 * 5, so a(14) = 2.
%e A087175 A000041(97) = 133230930 = 2*3*5*7*29*131*167, so a(97)=7.
%t A087175 Table[If[n==1,0,Length[FactorInteger[PartitionsP[n]]]],{n,1,100}] (* _Jonathan Sondow_, Aug 19 2011 *)
%o A087175 (PARI) a(n)={omega(numbpart(n))} \\ _Andrew Howroyd_, Dec 28 2017
%Y A087175 Cf. A000041, A001221, A085561. See also A071963, A192885.
%K A087175 nonn
%O A087175 1,7
%A A087175 _Reinhard Zumkeller_, Aug 23 2003