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 A133128 #8 Sep 17 2015 03:02:31
%S A133128 2,5,-3,10,-3,-5,17,-3,-5,-7,26,-3,-5,-7,-9,37,-3,-5,-7,-9,-11,50,-3,
%T A133128 -5,-7,-9,-11,-13,65,-3,-5,-7,-9,-11,-13,-15,82,-3,-5,-7,-9,-11,-13,
%U A133128 -15,-17,101,-3,-5,-7,-9,-11,-13,-15,-17,-19,122,-3,-5,-7,-9,-11,-13,-15,-17,-19,-21,145,-3,-5,-7,-9,-11,-13,-15,-17,-19,-21,-23,170,-3,-5,-7,-9,-11,-13
%N A133128 Triangle of first differences of A120070 with a leftmost column of A002522.
%C A133128 The flattened triangle is essentially the same as A141620.
%F A133128 T(n,0) = A002522(n+1).
%F A133128 T(n,m) = -2m-1, m>0 .
%F A133128 sum_{m=0..n} T(n,m) = 2 (row sums).
%F A133128 T(n,n) = -A005408(n), n>0.
%e A133128 The triangle starts
%e A133128 2;
%e A133128 5, -3;
%e A133128 10,-3,-5;
%e A133128 17,-3,-5,-7;
%e A133128 26,-3,-5,-7,-9;
%p A133128 A133128 := proc(n,m) if m>= 1 then -2*m-1 ; else (n+1)^2+1 ; fi; end: seq(seq(A133128(n,m),m=0..n),n=0..15) ; # _R. J. Mathar_, Nov 22 2009
%K A133128 sign,tabl,less,easy
%O A133128 0,1
%A A133128 _Paul Curtz_, Aug 27 2008
%E A133128 Edited and extended by _R. J. Mathar_, Nov 22 2009