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 A375046 #4 Sep 20 2024 06:08:44
%S A375046 3,1,12,7,1,72,54,13,1,720,612,184,23,1,12960,11736,3924,598,41,1,
%T A375046 440640,411984,145152,24256,1992,75,1,29082240,27631584,9992016,
%U A375046 1746048,155728,6942,141,1,3780691200,3621188160,1326593664,236978256,21990688,1058188
%N A375046 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = 2^n and t(x) = x+2. See Comments.
%C A375046 See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.
%e A375046 First 3 polynomials in s(x)**t(x) are
%e A375046 3 + x,
%e A375046 12 + 7 x + x^2,
%e A375046 72 + 54 x + 13 x^2 + x^3.
%e A375046 First 5 rows of array:
%e A375046 3 1
%e A375046 12 7 1
%e A375046 72 54 13 1
%e A375046 720 612 184 23 1
%e A375046 12960 11736 3924 598 41 1
%t A375046 s[n_] := 2^n x; t[n_] := x + 2;
%t A375046 u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
%t A375046 Table[Expand[u[n]], {n, 0, 10}]
%t A375046 Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]] (* array *)
%t A375046 Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]] (* sequence *)
%Y A375046 Cf. A000079, A139486 (column 1), A000012 (T(n,n+1)), A374848.
%K A375046 nonn,tabf
%O A375046 1,1
%A A375046 _Clark Kimberling_, Sep 15 2024