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 A204206 #9 Dec 25 2013 02:31:32 %S A204206 3,5,7,9,12,15,17,21,27,31,33,38,48,58,63,65,71,86,106,121,127,129, %T A204206 136,157,192,227,248,255,257,265,293,349,419,475,503,511,513,522,558, %U A204206 642,768,894,978,1014,1023,1025,1035,1080,1200,1410,1662,1872 %N A204206 Triangle based on (1,3/2,2) averaging array. %C A204206 See A204201 for a discussion and guide to other averaging arrays. %F A204206 From _Philippe Deléham_, Dec 24 2013: (Start) %F A204206 T(n,n) = A000225(n+1). %F A204206 Sum_{k=1..n} T(n,k) = A167667(n). %F A204206 T(n,k)=T(n-1,k)+3*T(n-1,k-1)-2*T(n-2,k-1)-2*T(n-2,k-2), T(1,1)=3, T(2,1)=5, T(2,2)=7, T(n,k)=0 if k<1 or if k>n. (End) %e A204206 First six rows: %e A204206 3 %e A204206 5...7 %e A204206 9...12...15 %e A204206 17..21...27...31 %e A204206 33..38...48...58...63 %e A204206 65..71...86...106..121..127 %t A204206 a = 1; r = 3/2; b = 2; %t A204206 t[1, 1] = r; %t A204206 t[n_, 1] := (a + t[n - 1, 1])/2; %t A204206 t[n_, n_] := (b + t[n - 1, n - 1])/2; %t A204206 t[n_, k_] := (t[n - 1, k - 1] + t[n - 1, k])/2; %t A204206 u[n_] := Table[t[n, k], {k, 1, n}] %t A204206 Table[u[n], {n, 1, 5}] (* averaging array *) %t A204206 u = Table[3 (1/2) (1/r) 2^n*u[n], {n, 1, 12}]; %t A204206 TableForm[u] (* A204206 triangle *) %t A204206 Flatten[u] (* A204206 sequence *) %Y A204206 Cf. A204201. %K A204206 nonn,tabl %O A204206 1,1 %A A204206 _Clark Kimberling_, Jan 12 2012