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 A153661 #22 Aug 24 2016 12:29:44
%S A153661 1,4,1,0,4,1,5,8,2,1,4,6,4,2,1,4,4,4,8,4,1,2,4,8,4,2,4,1,8,2,8,4,2,8,
%T A153661 2,1,0,0,0,0,0,0,4,2,1,4,10,16,8,4,10,16,8,4,1,16,4,16,8,4,16,4,12,16,
%U A153661 4,1,11,8,2,1,11,8,2,1,11,8,2,1,14,20,16,8,4,12,14,18,20,16,4,2,1,16,16,16,8,16,16,16,8,16,16,16,8,4,1
%N A153661 Triangle read by rows: R(n,k) = 2^(composite(n)-composite(k)) mod composite(n), 1<=k<=n.
%H A153661 G. C. Greubel, <a href="/A153661/b153661.txt">Table of n, a(n) for n = 1..1035</a>
%e A153661 Triangle begins:
%e A153661 1,
%e A153661 4, 1,
%e A153661 0, 4, 1,
%e A153661 5, 8, 2, 1,
%e A153661 4, 6, 4, 2, 1,
%e A153661 4, 4, 4, 8, 4, 1,
%p A153661 A153661 := proc(n,k) modp(2^(A002808(n)-A002808(k)),A002808(n)) ;end proc: # _R. J. Mathar_, Dec 15 2010
%t A153661 Composite[m_] := FixedPoint[m + PrimePi[#] + 1 &, m + PrimePi[m] + 1]; a[n_, k_] := Mod[2^(Composite[n] - Composite[k]), Composite[n]]; Table[a[n, k], {n, 1, 15}, {k, 1, n}]; Flatten[%] (* _G. C. Greubel_, Aug 24 2016 *)
%Y A153661 Cf. A000079, A002808, A175156.
%K A153661 nonn,tabl,easy,less
%O A153661 1,2
%A A153661 _Juri-Stepan Gerasimov_, Dec 12 2010
%E A153661 Terms corrected by _R. J. Mathar_, Dec 15 2010