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 A302391 #20 Dec 11 2023 21:45:53
%S A302391 0,0,1,1,3,2,4,3,5,4,6,5,8,7,10,8,10,7,12,9,13,9,15,11,17,12,17,15,18,
%T A302391 15,20,17,22,16,22,15,23,18,26,20,28,20,29,21,28,23,30,24,32,25,33,26,
%U A302391 34,23,36,27,37,27,39,29,41,29,40,34,42,34,44,36,46
%N A302391 Number of partitions of 2n into two parts with at least one nonsquarefree part.
%H A302391 <a href="/index/Par#part">Index entries for sequences related to partitions</a>
%F A302391 a(n) = Sum_{i=1..n} 1 - mu(2n-i)^2 * mu(i)^2, where mu is the Möbius function (A008683).
%F A302391 a(n) = n - A280226(n). - _Wesley Ivan Hurt_, Dec 11 2023
%t A302391 Table[Sum[1 - MoebiusMu[2 n - i]^2*MoebiusMu[i]^2, {i, n}], {n, 100}]
%o A302391 (Magma) [&+[(1-MoebiusMu(2*n-k)^2*MoebiusMu(k)^2): k in [1..n]]: n in [1..70]]; // _Vincenzo Librandi_, Apr 09 2018
%o A302391 (PARI) a(n) = sum(i=1, n, 1 - moebius(2*n-i)^2*moebius(i)^2); \\ _Michel Marcus_, Apr 09 2018
%Y A302391 Cf. A008683, A013929, A280226, A294097.
%K A302391 nonn
%O A302391 1,5
%A A302391 _Wesley Ivan Hurt_, Apr 06 2018