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 A133600 #13 Jan 12 2020 20:21:10
%S A133600 1,4,7,16,28,64,112,256,448,1024,1792,4096,7168,16384,28672,65536,
%T A133600 114688,262144,458752,1048576,1835008,4194304,7340032,16777216,
%U A133600 29360128,67108864,117440512,268435456,469762048,1073741824,1879048192
%N A133600 Row sums of triangle A133599.
%H A133600 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,4).
%F A133600 For even-indexed terms, a(n) = 2^n. For odd-indexed terms, a(n) = 7 * 2^(n-3).
%F A133600 G.f.: -x*(x+1)*(3*x+1)/(2*x-1)/(2*x+1). - _R. J. Mathar_, Nov 14 2007
%F A133600 a(n) = 4*a(n-2) for n > 3; a(1) = 1, a(2) = 4, a(3) = 7. - _Klaus Brockhaus_, Nov 26 2009
%e A133600 a(4) = 16 = sum of row 4 terms of triangle A133599 = (3 + 7 + 5 + 1).
%e A133600 a(4) = 16 = 2^4.
%e A133600 a(7) = 112 = 7 * 2^4 = 7 * 16.
%t A133600 LinearRecurrence[{0,4},{1,4,7},40] (* _Harvey P. Dale_, Jan 12 2020 *)
%o A133600 (PARI) {vector(31, n, if(n==1, 1, if(n%2>0, 7*2^(n-3), 2^n)))} /* _Klaus Brockhaus_, Nov 26 2009 */
%Y A133600 Cf. A133599, A000302 (bisection), A002042 (bisection, n>2).
%K A133600 nonn,easy
%O A133600 1,2
%A A133600 _Gary W. Adamson_, Sep 18 2007