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 A128620 #21 Mar 15 2024 03:41:32
%S A128620 1,1,4,6,15,24,52,84,170,275,534,864,1631,2639,4880,7896,14373,23256,
%T A128620 41810,67650,120406,194821,343884,556416,975325,1578109,2749852,
%U A128620 4449354,7713435,12480600,21540304,34852944,59917826,96949079,166094370,268746336
%N A128620 Row sums of A128619.
%C A128620 Diagonals sums of A199512. - _Philippe Deléham_, Dec 01 2013
%H A128620 G. C. Greubel, <a href="/A128620/b128620.txt">Table of n, a(n) for n = 0..1000</a>
%H A128620 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,4,-3,-4,1,1).
%F A128620 a(n) = floor((n+2)/2)*Fibonacci(n+1). - _Philippe Deléham_, Dec 01 2013
%F A128620 G.f.: (1 - x^2 + x^3)/((1 + x - x^2)*(1 - x - x^2)^2). - _Bruno Berselli_, Dec 02 2013
%e A128620 a(5) = 15 = sum of row 5 in A128619: (5 + 0 + 5 + 0 + 5).
%t A128620 LinearRecurrence[{1,4,-3,-4,1,1}, {1,1,4,6,15,24}, 40] (* or *)
%t A128620 Table[Floor[(n+2)/2] Fibonacci[n+1], {n, 0, 40}] (* _Bruno Berselli_, Dec 02 2013 *)
%o A128620 (PARI) a(n)= ((n+2)\2) * fibonacci(n+1); \\ _Michel Marcus_, Dec 02 2013
%o A128620 (Magma) [Floor((n+2)/2)*Fibonacci(n+1): n in [0..40]]; // _G. C. Greubel_, Mar 15 2024
%o A128620 (SageMath) [int((n+2)/2)*fibonacci(n+1) for n in range(41)] # _G. C. Greubel_, Mar 15 2024
%Y A128620 Cf. A000045, A128619, A199512.
%K A128620 nonn,easy
%O A128620 0,3
%A A128620 _Gary W. Adamson_, Mar 14 2007
%E A128620 More terms from _Philippe Deléham_, Dec 01 2013
%E A128620 a(31) corrected from _Bruno Berselli_, Dec 02 2013