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 A105596 #12 Aug 01 2023 07:37:59 %S A105596 1,5,13,17,25,25,33,21,9,-15,-23,-3,-11,-31,-47,-35,5,-47,-83,-75, %T A105596 -211,-295,-267,-267,-99,-107,-159,-415,-347,-679,-279,-583,-395,-839, %U A105596 -1031,-1291,-1139,-1883,-1519,-1643,-855,-1591,-1571,-1851,-1195,-2419,-1923,-2179,-891,-1919,-2535 %N A105596 a(n) = Sum_{k=0..n} A105595(k)*(-1)^k*A105595(n-k) (interpolated zeros suppressed). %C A105596 Conjecture : a(2n)=1 mod 4 for all n, a(2n+1)=0 for all n. %p A105596 A105596 := proc(n) %p A105596 add(A105595(k)*(-1)^k*A105595(2*n-k),k=0..2*n) ; %p A105596 end proc: %p A105596 seq(A105596(n),n=0..50) ; # _R. J. Mathar_, Nov 28 2014 %t A105596 A105594[n_, k_] := A105594[n, k] = Sum[Abs[MoebiusMu[ Binomial[n, j]]*Mod[Binomial[j, k], 2]], {j, 0, n}]//Mod[#, 2]&; %t A105596 A105595[n_] := Sum[A105594[n, k], {k, 0, n}]; %t A105596 a[n_] := Sum[A105595[k]*(-1)^k*A105595[2n - k], {k, 0, 2n}]; %t A105596 Table[a[n], {n, 0, 50}] (* _Jean-François Alcover_, Aug 01 2023, after _R. J. Mathar_ *) %Y A105596 Cf. A105594, A105595. %K A105596 easy,sign %O A105596 0,2 %A A105596 _Paul Barry_, Apr 14 2005