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 A154784 #7 Feb 03 2019 17:17:17
%S A154784 0,4,6,16,10,24,28,32,54,60,44,96,52,56,120,96,102,144,76,120,210,176,
%T A154784 138,288,200,156,324,168,174,420,186,320,396,204,350,504,370,380,546,
%U A154784 400,328,756,344,352,900,368,376,672,392,600
%N A154784 Row sums of triangle in A154721.
%C A154784 a(n) is even for all n.
%H A154784 Nathaniel Johnston, <a href="/A154784/b154784.txt">Table of n, a(n) for n = 1..10000</a>
%F A154784 a(n) = A154783(n) - n.
%p A154784 isnotcomp:=proc(n)return (n=1 or isprime(n)) end:
%p A154784 for n from 1 to 50 do rsum:=0: for k from 1 to 2*n-1 do if(not k=n and (isnotcomp(k) and isnotcomp(2*n-k)))then rsum:=rsum+k:fi:od: printf("%d, ",rsum):od: # _Nathaniel Johnston_, Apr 19 2011
%Y A154784 Cf. A154720, A154721, A154723, A154783, A154785, A154786.
%K A154784 easy,nonn
%O A154784 1,2
%A A154784 _Omar E. Pol_, Jan 15 2009
%E A154784 Edited by _Omar E. Pol_, Jan 17 2009
%E A154784 a(11)-a(50) from _Nathaniel Johnston_, Apr 19 2011