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 A194084 #12 Jul 11 2012 14:40:58 %S A194084 0,3,0,3,0,3,3,0,0,0,3,0,-3,0,-3,3,0,-6,0,-3,0,3,0,-9,0,0,0,3,3,0,-12, %T A194084 0,6,0,6,0,3,0,-15,0,15,0,6,0,-3,3,0,-18,0,27,0,0,0,-9,0 %N A194084 Triangle read by rows: a(n)=A135929(n) + A192011(n). Row n gives coefficients of polynomials BC(n,x) in order of decreasing exponents. %C A194084 0, %C A194084 3, 0, %C A194084 3, 0, 3, %C A194084 3, 0, 0, 0, %C A194084 3, 0, -3, 0, -3, %C A194084 3, 0, -6, 0, -3, 0. %C A194084 Multiples of 3. %C A194084 Row sum (from the second) is period 6: 3*A057079(n),"from" A057083 (scaled Chebyshev U(n,x)). %C A194084 If a(0)=-3, a(n)=3*A192174(n). %F A194084 BC(0,x)=0, BC(1,x)=3*x, BC(2,x)=3*x^2+3, BC(n,x)=x*BC(n-1,x) - BC(n-2,x), n > 2. %e A194084 a(0)=1-1=0, a(1)=1+2=3, a(2)=0+0=0. %K A194084 sign,tabl %O A194084 0,2 %A A194084 _Paul Curtz_, Aug 14 2011