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 A173741 #11 Feb 13 2021 14:50:15
%S A173741 1,1,1,1,6,1,1,7,7,1,1,8,10,8,1,1,9,14,14,9,1,1,10,19,24,19,10,1,1,11,
%T A173741 25,39,39,25,11,1,1,12,32,60,74,60,32,12,1,1,13,40,88,130,130,88,40,
%U A173741 13,1,1,14,49,124,214,256,214,124,49,14,1,1,15,59,169,334,466,466,334,169,59,15,1
%N A173741 T(n,k) = binomial(n,k) + 4 for 1 <= k <= n - 1, n >= 2, and T(n,0) = T(n,n) = 1 for n >= 0, triangle read by rows.
%C A173741 For n >= 1, row n sums to 2*A100314(n).
%H A173741 G. C. Greubel, <a href="/A173741/b173741.txt">Rows n = 0..100 of the triangle, flattened</a>
%F A173741 From _Franck Maminirina Ramaharo_, Dec 09 2018:(Start)
%F A173741 T(n,k) = A007318(n,k) + 2*(1 - A103451(n,k)).
%F A173741 T(n,k) = 5*A007318(n,k) - 4*A132044(n,k).
%F A173741 n-th row polynomial is 2*(1 - (-1)^(2^n)) + (1 + x)^n + 4*(x - x^n)/(1 - x).
%F A173741 G.f.: (1 - (1 + x)*y + 5*x*y^2 - 4*(x + x^2)*y^3)/((1 - y)*(1 - x*y)*(1 - y - x*y)).
%F A173741 E.g.f.: (4 - 4*x + 4*x*exp(y) - 4*exp(x*y) + (1 - x)*exp((1 + x)*y))/(1 - x). (End)
%F A173741 Sum_{k=0..n} T(n, k) = 2^n + 4*(n - 1 + [n=0]) = 2*A100314(n). - _G. C. Greubel_, Feb 13 2021
%e A173741 Triangle begins:
%e A173741 1;
%e A173741 1, 1;
%e A173741 1, 6, 1;
%e A173741 1, 7, 7, 1;
%e A173741 1, 8, 10, 8, 1;
%e A173741 1, 9, 14, 14, 9, 1;
%e A173741 1, 10, 19, 24, 19, 10, 1;
%e A173741 1, 11, 25, 39, 39, 25, 11, 1;
%e A173741 1, 12, 32, 60, 74, 60, 32, 12, 1;
%e A173741 1, 13, 40, 88, 130, 130, 88, 40, 13, 1;
%e A173741 1, 14, 49, 124, 214, 256, 214, 124, 49, 14, 1;
%e A173741 ...
%t A173741 T[n_, m_] = Binomial[n, m] + 4*If[m*(n - m) > 0, 1, 0];
%t A173741 Flatten[Table[T[n, m], {n, 0, 10}, {m, 0, n}]]
%o A173741 (Maxima) T(n,k) := if k = 0 or k = n then 1 else binomial(n, k) + 4$
%o A173741 create_list(T(n, k), n, 0, 12, k, 0, n); /* _Franck Maminirina Ramaharo_, Dec 09 2018 */
%o A173741 (Sage)
%o A173741 def T(n, k): return 1 if (k==0 or k==n) else binomial(n, k) + 4
%o A173741 flatten([[T(n,k) for k in (0..n)] for n in (0..12)]) # _G. C. Greubel_, Feb 13 2021
%o A173741 (Magma)
%o A173741 T:= func< n,k | k eq 0 or k eq n select 1 else Binomial(n,k) + 4 >;
%o A173741 [T(n,k): k in [0..n], n in [0..12]]; // _G. C. Greubel_, Feb 13 2021
%Y A173741 Cf. A100314, A103451, A156050.
%Y A173741 Sequences of the form binomial(n, k) + q: A132823 (q=-2), A132044 (q=-1), A007318 (q=0), A132735 (q=1), A173740 (q=2), this sequence (q=4), A173742 (q=6).
%K A173741 nonn,tabl,easy
%O A173741 0,5
%A A173741 _Roger L. Bagula_, Feb 23 2010
%E A173741 Edited and name clarified by _Franck Maminirina Ramaharo_, Dec 09 2018