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 A286227 #9 Feb 16 2025 08:33:44
%S A286227 1,1,1,1,2,3,5,7,10,15,24,36,53,78,118,179,271,405,605,907,1366,2055,
%T A286227 3086,4628,6948,10440,15689,23560,35371,53110,79771,119821,179958,
%U A286227 270243,405833,609495,915394,1374780,2064647,3100680,4656676,6993575,10503180,15773877,23689467,35577360
%N A286227 Number of compositions (ordered partitions) of n into parts with an even number of prime divisors (counted with multiplicity).
%H A286227 Amiram Eldar, <a href="/A286227/b286227.txt">Table of n, a(n) for n = 0..5000</a>
%H A286227 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimeFactor.html">Prime Factor</a>
%H A286227 <a href="/index/Com#comp">Index entries for sequences related to compositions</a>
%F A286227 G.f.: 1/(1 - Sum_{k>=1} x^A028260(k)).
%e A286227 a(6) = 5 because we have [6], [4, 1, 1], [1, 4, 1], [1, 1, 4] and [1, 1, 1, 1, 1, 1].
%t A286227 nmax = 45; CoefficientList[Series[1/(1 - Sum[Boole[EvenQ[PrimeOmega[k]]] x^k, {k, 1, nmax}]), {x, 0, nmax}], x]
%Y A286227 Cf. A028260, A286219, A286223, A286225, A286226.
%K A286227 nonn
%O A286227 0,5
%A A286227 _Ilya Gutkovskiy_, May 04 2017