cp's OEIS Frontend

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.

A070914 Array read by antidiagonals giving number of paths up and left from (0,0) to (n,kn) where x/y <= k for all intermediate points.

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%I A070914 #44 Jan 05 2025 19:51:37
%S A070914 1,1,1,1,1,1,1,1,2,1,1,1,3,5,1,1,1,4,12,14,1,1,1,5,22,55,42,1,1,1,6,
%T A070914 35,140,273,132,1,1,1,7,51,285,969,1428,429,1,1,1,8,70,506,2530,7084,
%U A070914 7752,1430,1,1,1,9,92,819,5481,23751,53820,43263,4862,1,1,1,10,117,1240
%N A070914 Array read by antidiagonals giving number of paths up and left from (0,0) to (n,kn) where x/y <= k for all intermediate points.
%C A070914 Also related to dissections of polygons and enumeration of trees.
%C A070914 Number of dissections of a polygon into n (k+2)-gons by nonintersecting diagonals. All dissections are counted separately. See A295260 for nonequivalent solutions up to rotation and reflection. - _Andrew Howroyd_, Nov 20 2017
%C A070914 Number of rooted polyominoes composed of n (k+2)-gonal cells of the hyperbolic (Euclidean for k=0) regular tiling with Schläfli symbol {k+2,oo}. A rooted polyomino has one external edge identified, and chiral pairs are counted as two. For k>0, a stereographic projection of the {k+2,oo} tiling on the Poincaré disk can be obtained via the Christensson link. - _Robert A. Russell_, Jan 27 2024
%H A070914 Alois P. Heinz, <a href="/A070914/b070914.txt">Antidiagonals n = 0..140, flattened</a>
%H A070914 Malin Christensson, <a href="http://malinc.se/m/ImageTiling.php">Make hyperbolic tilings of images</a>, web page, 2019.
%H A070914 Peter Hilton and Jean Pedersen, <a href="http://www.math.uakron.edu/~cossey/636papers/hilton%20and%20pedersen.pdf">Catalan Numbers, Their Generalization, and Their Uses</a>, The Mathematical Intelligencer, March 1991, Volume 13, Issue 2, pp. 64-75.
%H A070914 V. E. Hoggatt, Jr. and M. Bicknell, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/14-5/hoggatt1.pdf">Catalan and related sequences arising from inverses of Pascal's triangle matrices</a>, Fib. Quart., 14 (1976), 395-405.
%F A070914 T(n, k) = binomial(n*(k+1), n)/(n*k+1) = A071201(n, k*n) = A071201(n, k*n+1) = A071202(n, k*n+1) = A062993(n+k-1, k-1).
%F A070914 If P(k,x) = Sum_{n>=0} T(n,k)*x^n is the g.f. of column k (k>=0), then P(k,x) = exp(1/(k+1)*(Sum_{j>0} (1/j)*binomial((k+1)*j,j)*x^j)). - _Werner Schulte_, Oct 13 2015
%e A070914 Rows start:
%e A070914 ===========================================================
%e A070914 n\k| 0     1      2       3        4        5         6
%e A070914 ---|-------------------------------------------------------
%e A070914 0  | 1,    1,     1,      1,       1,       1,        1 ...
%e A070914 1  | 1,    1,     1,      1,       1,       1,        1 ...
%e A070914 2  | 1,    2,     3,      4,       5,       6,        7 ...
%e A070914 3  | 1,    5,    12,     22,      35,      51,       70 ...
%e A070914 4  | 1,   14,    55,    140,     285,     506,      819 ...
%e A070914 5  | 1,   42,   273,    969,    2530,    5481,    10472 ...
%e A070914 6  | 1,  132,  1428,   7084,   23751,   62832,   141778 ...
%e A070914 7  | 1,  429,  7752,  53820,  231880,  749398,  1997688 ...
%e A070914 8  | 1, 1430, 43263, 420732, 2330445, 9203634, 28989675 ...
%e A070914 ...
%p A070914 A:= (n, k)-> binomial((k+1)*n, n)/(k*n+1):
%p A070914 seq(seq(A(n, d-n), n=0..d), d=0..12);  # _Alois P. Heinz_, Mar 25 2015
%t A070914 T[n_, k_] = Binomial[n(k+1), n]/(k*n+1); Flatten[Table[T[n-k, k], {n, 0, 9}, {k, n, 0, -1}]] (* _Jean-François Alcover_, Apr 08 2016 *)
%o A070914 (PARI) T(n, k) = binomial(n*(k+1), n)/(n*k+1); \\ _Andrew Howroyd_, Nov 20 2017
%Y A070914 Rows include A000012 (twice), A000027, A000326.
%Y A070914 Columns include A000012, A000108 (Catalan), A001764, A002293, A002294, A002295, A002296, A007556, A062994, A059968.
%Y A070914 Reflected version of A062993 (which is the main entry).
%Y A070914 Cf. A295260.
%Y A070914 Polyominoes: A295224 (oriented), A295260 (unoriented).
%K A070914 nonn,tabl
%O A070914 0,9
%A A070914 _Henry Bottomley_, May 20 2002