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 A274180 #21 Jun 17 2016 09:04:45
%S A274180 1,31,341,6483,69905,2027247,21041413,417263459,4311810305,
%T A274180 133666119455,1461703693397,27806864656979,299071474565137,
%U A274180 8708265758097903,90161415181374469,1785159701350222947,18447025552981295105
%N A274180 a(n) = Sum_{k=0..4n} (A035343(n,k) mod 2) * 2^k.
%C A274180 a(n) is a binary palindrome (A006995) of 4n+1 bits since A035343(n,k) = A035343(n,4n-k), k=0..4n and A035343(n,0) = A035343(n,4n) = 1.
%H A274180 Gheorghe Coserea, <a href="/A274180/b274180.txt">Table of n, a(n) for n = 0..200</a>
%o A274180 (PARI)
%o A274180 a(n) = subst(lift(Pol(Mod([1, 1, 1, 1, 1], 2), 'x)^n), 'x, 2);
%o A274180 vector(17,n,a(n-1))
%Y A274180 Cf. A035343.
%K A274180 nonn,base
%O A274180 0,2
%A A274180 _Gheorghe Coserea_, Jun 12 2016