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 A228638 #7 Aug 29 2013 10:37:08
%S A228638 0,0,0,1,2,-5,12,-28,32,-36,-44,-51,90,-129,-572,560,-228,-1265,-3752,
%T A228638 -7344,-7168,-5200,-1800,22225,-223908,-3353049,-16485870,-46205099,
%U A228638 57203700,262750475,-1758254750,-4839494944,-8039222088,8145218368,45619374914,-1229448140891,-1178481640872,-942903100573,1256162791268,-805110454771
%N A228638 Determinant of the n X n matrix with (i,j)-entry equal to 1 or 0 according as |i-j| is prime or not.
%C A228638 Conjecture: a(n) is nonzero for any n > 3.
%H A228638 Zhi-Wei Sun, <a href="/A228638/b228638.txt">Table of n, a(n) for n = 1..300</a>
%e A228638 a(1) = 0 since |1-1| = 0 is not a prime.
%t A228638 a[n_]:=Det[Table[If[PrimeQ[Abs[i-j]]==True,1,0],{i,1,n},{j,1,n}]]
%t A228638 Table[a[n],{n,1,50}]
%Y A228638 Cf. A228626, A228615, A228616, A228623, A228624.
%K A228638 sign
%O A228638 1,5
%A A228638 _Zhi-Wei Sun_, Aug 28 2013