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.

Showing 1-10 of 12 results. Next

A262809 Number A(n,k) of lattice paths from {n}^k to {0}^k using steps that decrement one or more components by one; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 13, 13, 1, 1, 1, 75, 409, 63, 1, 1, 1, 541, 23917, 16081, 321, 1, 1, 1, 4683, 2244361, 10681263, 699121, 1683, 1, 1, 1, 47293, 308682013, 14638956721, 5552351121, 32193253, 8989, 1, 1, 1, 545835, 58514835289, 35941784497263, 117029959485121, 3147728203035, 1538743249, 48639, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Oct 02 2015

Keywords

Comments

Also, A(n,k) is the number of alignments for k sequences of length n each (Slowinski 1998).
Row r > 0 is asymptotic to sqrt(r*Pi) * (r^(r-1)/(r-1)!)^n * n^(r*n+1/2) / (2^(r/2) * exp(r*n) * (log(2))^(r*n+1)), or equivalently to sqrt(r) * (r^(r-1)/(r-1)!)^n * (n!)^r / (2^r * (Pi*n)^((r-1)/2) * (log(2))^(r*n+1)). - Vaclav Kotesovec, Mar 23 2016
From Vaclav Kotesovec, Mar 23 2016: (Start)
Column k > 0 is asymptotic to sqrt(c(k)) * d(k)^n / (Pi*n)^((k-1)/2), where c(k) and d(k) are roots of polynomial equations of degree k, independent on n.
---------------------------------------------------
k d(k)
---------------------------------------------------
2 5.8284271247461900976033774484193...
3 56.9476283720414911685286267804411...
4 780.2794068067951456595241495989622...
5 13755.2719024115081712083954421541320...
6 296476.9162644200814909862281498491264...
7 7553550.6198338218721069097516499501996...
8 222082591.6017202421029000117685530884167...
9 7400694480.0494436216324852038000444393262...
10 275651917450.6709238286995776605620357737005...
---------------------------------------------------
d(k) is a root of polynomial:
---------------------------------------------------
k=2, 1 - 6*d + d^2
k=3, -1 + 3*d - 57*d^2 + d^3
k=4, 1 - 12*d - 218*d^2 - 780*d^3 + d^4
k=5, -1 + 5*d - 1260*d^2 - 3740*d^3 - 13755*d^4 + d^5
k=6, 1 - 18*d - 5397*d^2 - 123696*d^3 + 321303*d^4 - 296478*d^5 + d^6
k=7, -1 + 7*d - 24031*d^2 - 374521*d^3 - 24850385*d^4 + 17978709*d^5 - 7553553*d^6 + d^7
k=8, 1 - 24*d - 102692*d^2 - 9298344*d^3 + 536208070*d^4 - 7106080680*d^5 - 1688209700*d^6 - 222082584*d^7 + d^8
(End)
d(k) = (2^(1/k) - 1)^(-k). - David Bevan, Apr 07 2022
d(k) is asymptotic to (k/log(2))^k/sqrt(2). - David Bevan, Apr 07 2022
A(n,k) is the number of binary matrices with k columns and any number of nonzero rows with n ones in every column. - Andrew Howroyd, Jan 23 2020

Examples

			A(2,2) = 13: [(2,2),(1,2),(0,2),(0,1),(0,0)], [(2,2),(1,2),(0,1),(0,0)], [(2,2),(1,2),(1,1),(0,1),(0,0)], [(2,2),(1,2),(1,1),(0,0)], [(2,2),(1,2),(1,1),(1,0),(0,0)], [(2,2),(2,1),(1,1),(0,1),(0,0)], [(2,2),(2,1),(1,1),(0,0)], [(2,2),(2,1),(1,1),(1,0),(0,0)], [(2,2),(2,1),(2,0),(0,1),(0,0)], [(2,2),(2,1),(1,0),(0,0)], [(2,2),(1,1),(0,1),(0,0)], [(2,2),(1,1),(0,0)], [(2,2),(1,1),(1,0),(0,0)].
Square array A(n,k) begins:
  1, 1,    1,        1,             1,                   1, ...
  1, 1,    3,       13,            75,                 541, ...
  1, 1,   13,      409,         23917,             2244361, ...
  1, 1,   63,    16081,      10681263,         14638956721, ...
  1, 1,  321,   699121,    5552351121,     117029959485121, ...
  1, 1, 1683, 32193253, 3147728203035, 1050740615666453461, ...
		

Crossrefs

Columns: A000012 (k=0 and k=1), A001850 (k=2), A126086 (k=3), A263064 (k=4), A263065 (k=5), A263066 (k=6), A263067 (k=7), A263068 (k=8), A263069 (k=9), A263070 (k=10).
Rows: A000012 (n=0), A000670 (n=1), A055203 (n=2), A062208 (n=3), A062205 (n=4), A263061 (n=5), A263062 (n=6), A062204 (n=7), A263063 (n=8), A263071 (n=9), A263072 (n=10).
Main diagonal: A262810.

Programs

  • Maple
    A:= (n, k)-> add(add((-1)^i*binomial(j, i)*
         binomial(j-i, n)^k, i=0..j), j=0..k*n):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    A[, 0] =  1; A[n, k_] := Sum[Sum[(-1)^i*Binomial[j, i]*Binomial[j - i, n]^k, {i, 0, j}], {j, 0, k*n}];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Jul 22 2016, after Alois P. Heinz *)
  • PARI
    T(n,k) = {my(m=n*k); sum(j=0, m, binomial(j,n)^k*sum(i=j, m, (-1)^(i-j)*binomial(i, j)))} \\ Andrew Howroyd, Jan 23 2020

Formula

A(n,k) = Sum_{j=0..k*n} Sum_{i=0..j} (-1)^i*C(j,i)*C(j-i,n)^k.
A(n,k) = Sum_{i >= 0} binomial(i,n)^k/2^(i+1). - Peter Bala, Jan 30 2018
A(n,k) = Sum_{j=0..n*k} binomial(j,n)^k * Sum_{i=j..n*k} (-1)^(i-j) * binomial(i,j). - Andrew Howroyd, Jan 23 2020

A263159 Number A(n,k) of lattice paths starting at {n}^k and ending when k or any component equals 0, using steps that decrement one or more components by one; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 7, 13, 1, 1, 1, 15, 157, 63, 1, 1, 1, 31, 2101, 5419, 321, 1, 1, 1, 63, 32461, 717795, 220561, 1683, 1, 1, 1, 127, 580693, 142090291, 328504401, 9763807, 8989, 1, 1, 1, 255, 11917837, 39991899123, 944362553521, 172924236255, 454635973, 48639, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Oct 11 2015

Keywords

Examples

			Square array A(n,k) begins:
  1, 1,    1,       1,            1,                1, ...
  1, 1,    3,       7,           15,               31, ...
  1, 1,   13,     157,         2101,            32461, ...
  1, 1,   63,    5419,       717795,        142090291, ...
  1, 1,  321,  220561,    328504401,     944362553521, ...
  1, 1, 1683, 9763807, 172924236255, 7622403922836151, ...
		

Crossrefs

Rows n=0-1 give: A000012, A255047.
Main diagonal gives A263160.

Programs

  • Maple
    s:= proc(n) option remember; `if`(n=0, {[]},
          map(x-> [[x[], 0], [x[], 1]][], s(n-1)))
        end:
    b:= proc(l) option remember; `if`(l=[] or l[1]=0, 1,
           add((p-> `if`(p[1]<0, 0, `if`(p[1]=0, 1, b(p)))
           )(sort(l-x)), x=s(nops(l)) minus {[0$nops(l)]}))
        end:
    A:= (n, k)-> b([n$k]):
    seq(seq(A(n,d-n), n=0..d), d=0..10);
  • Mathematica
    g[k_] := Table[Reverse[IntegerDigits[n, 2]][[;;k]], {n, 2^k+1, 2^(k+1)-1}];
    b[l_] := b[l] = If[l[[1]] == 0, 1, Sum[b[Sort[l - h]], {h, g[k]}]];
    a[n_, k_] := If[n == 0 || k == 0 || k == 1, 1, b[Table[n, {k}]]];
    Table[a[n-k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Apr 25 2020, after Alois P. Heinz in A115866 *)

A089759 Table T(n,k), 0<=k, 0<=n, read by antidiagonals, defined by T(n,k) = (k*n)! / (n!)^k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 6, 6, 1, 1, 1, 24, 90, 20, 1, 1, 1, 120, 2520, 1680, 70, 1, 1, 1, 720, 113400, 369600, 34650, 252, 1, 1, 1, 5040, 7484400, 168168000, 63063000, 756756, 924, 1, 1, 1, 40320, 681080400, 137225088000, 305540235000, 11732745024, 17153136, 3432, 1, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 08 2004; revised Jun 08 2005

Keywords

Comments

T(n,k) is the number of lattice paths from {n}^k to {0}^k using steps that decrement one component by 1. - Alois P. Heinz, May 06 2013

Examples

			Row n=0: 1, 1,   1,      1,           1,               1, ... A000012
Row n=1: 1, 1,   2,      6,          24,             120, ... A000142
Row n=2: 1, 1,   6,     90,        2520,          113400, ... A000680
Row n=3: 1, 1,  20,   1680,      369600,       168168000, ... A014606
Row n=4: 1, 1,  70,  34650,    63063000,    305540235000, ... A014608
Row n=5: 1, 1, 252, 756756, 11732745024, 623360743125120, ... A014609
		

Crossrefs

Cf. A000680, A014606, A014608, A014609, A000984, A187783 (transposed version).
Main diagonal gives A034841.

Programs

  • Maple
    T:= (n, k)-> (k*n)!/(n!)^k:
    seq(seq(T(n, d-n), n=0..d), d=0..10);  # Alois P. Heinz, Aug 16 2012
  • Mathematica
    T[n_, k_] := (k*n)!/(n!)^k; Table[T[n-k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 19 2015 *)

Extensions

Corrected by Alois P. Heinz, Aug 16 2012

A229142 Number A(n,k) of lattice paths from {n}^k to {0}^k using steps that decrement one component or all components by 1; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 7, 13, 1, 1, 1, 25, 115, 63, 1, 1, 1, 121, 2641, 2371, 321, 1, 1, 1, 721, 114121, 392641, 54091, 1683, 1, 1, 1, 5041, 7489441, 169417921, 67982041, 1307377, 8989, 1, 1, 1, 40321, 681120721, 137322405361, 308238414121, 12838867105, 32803219, 48639, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 23 2013

Keywords

Comments

Column k is the diagonal of the rational function 1 / (1 - Sum_{j=1..k} x_j - Product_{j=1..k} x_j) for k>1. - Seiichi Manyama, Jul 10 2020

Examples

			A(1,3) = 3*2+1 = 7:
          (0,1,1)-(0,0,1)
         /       X       \
  (1,1,1)-(1,0,1) (0,1,0)-(0,0,0)
       \ \       X       / /
        \ (1,1,0)-(1,0,0) /
         `---------------´
Square array A(n,k) begins:
  1, 1,    1,       1,           1,               1, ...
  1, 1,    3,       7,          25,             121, ...
  1, 1,   13,     115,        2641,          114121, ...
  1, 1,   63,    2371,      392641,       169417921, ...
  1, 1,  321,   54091,    67982041,    308238414121, ...
  1, 1, 1683, 1307377, 12838867105, 629799991355641, ...
		

Crossrefs

Rows n=0-1 give: A000012, A038507 (for k>1).
Main diagonal gives: A229267.

Programs

  • Maple
    with(combinat):
    A:= (n,k)-> `if`(k<2, 1, add(multinomial(n+(k-1)*j, n-j, j$k), j=0..n)):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    a[, 0] = a[, 1] = 1; a[n_, k_] := Sum[Product[Binomial[n+j*m, m], {j, 0, k-1}], {m, 0, n}]; Table[a[n-k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 11 2013 *)

Formula

A(n,k) = Sum_{j=0..n} multinomial(n+(k-1)*j; n-j, {j}^k) for k>1, A(n,0) = A(n,1) = 1.
G.f. of column k: Sum_{j>=0} (k*j)!/j!^k * x^j / (1-x)^(k*j+1). for k>1. - Seiichi Manyama, Jul 10 2020

A210472 Number A(n,k) of paths starting at {n}^k to a border position where one component equals 0 using steps that decrement one component by 1; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 6, 1, 0, 1, 4, 33, 20, 1, 0, 1, 5, 196, 543, 70, 1, 0, 1, 6, 1305, 22096, 10497, 252, 1, 0, 1, 7, 9786, 1304045, 3323092, 220503, 924, 1, 0, 1, 8, 82201, 106478916, 1971644785, 574346824, 4870401, 3432, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Jan 22 2013

Keywords

Examples

			A(0,3) = 1: [(0,0,0)].
A(1,1) = 1: [(1), (0)].
A(1,2) = 2: [(1,1), (0,1)], [(1,1), (1,0)].
A(1,3) = 3: [(1,1,1), (0,1,1)], [(1,1,1), (1,0,1)], [(1,1,1), (1,1,0)].
A(2,1) = 1: [(2), (1), (0)].
A(2,2) = 6: [(2,2), (1,2), (0,2)], [(2,2), (1,2), (1,1), (0,1)], [(2,2), (1,2), (1,1), (1,0)], [(2,2), (2,1), (1,1), (0,1)], [(2,2), (2,1), (1,1), (1,0)], [(2,2), (2,1), (2,0)].
Square array A(n,k) begins:
  0, 1,   1,      1,         1,             1, ...
  0, 1,   2,      3,         4,             5, ...
  0, 1,   6,     33,       196,          1305, ...
  0, 1,  20,    543,     22096,       1304045, ...
  0, 1,  70,  10497,   3323092,    1971644785, ...
  0, 1, 252, 220503, 574346824, 3617739047205, ...
		

Crossrefs

Columns k=0-4 give: A000004, A000012, A000984, A209245, A209288.
Rows n=0-3 give: A057427, A001477, A093964, A210486.
Main diagonal gives A276490.
Cf. A089759 (unrestricted paths), A225094, A262809, A263159.

Programs

  • Maple
    b:= proc() option remember; `if`(nargs=0, 0, `if`(args[1]=0, 1,
          add(b(sort(subsop(i=args[i]-1, [args]))[]), i=1..nargs)))
        end:
    A:= (n, k)-> b(n$k):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    b[] = 0; b[args__] := b[args] = If[First[{args}] == 0, 1, Sum[b @@ Sort[ReplacePart[{args}, i -> {args}[[i]] - 1]], {i, 1, Length[{args}]}]]; a[n_, k_] := b @@ Array[n&, k]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Dec 12 2013, translated from Maple *)

A229345 Number A(n,k) of lattice paths from {n}^k to {0}^k using steps that decrement one component or all components by the same positive integer; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 7, 22, 4, 1, 1, 25, 248, 188, 8, 1, 1, 121, 6506, 11380, 1712, 16, 1, 1, 721, 292442, 2359348, 577124, 16098, 32, 1, 1, 5041, 19450082, 1088626684, 991365512, 30970588, 154352, 64, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 24 2013

Keywords

Examples

			A(2,2) = 22: [(2,2),(1,1),(0,0)], [(2,2),(1,1),(0,1),(0,0)], [(2,2),(1,1),(1,0),(0,0)], [(2,2),(0,0)], [(2,2),(1,2),(0,1),(0,0)], [(2,2),(1,2),(0,2),(0,1),(0,0)], [(2,2),(1,2),(0,2),(0,0)], [(2,2),(1,2),(1,1),(0,0)], [(2,2),(1,2),(1,1),(0,1),(0,0)], [(2,2),(1,2),(1,1),(1,0),(0,0)], [(2,2),(1,2),(1,0),(0,0)], [(2,2),(0,2),(0,1),(0,0)], [(2,2),(0,2),(0,0)], [(2,2),(2,1),(1,0),(0,0)], [(2,2),(2,1),(1,1),(0,0)], [(2,2),(2,1),(1,1),(0,1),(0,0)], [(2,2),(2,1),(1,1),(1,0),(0,0)], [(2,2),(2,1),(0,1),(0,0)], [(2,2),(2,1),(2,0),(1,0),(0,0)], [(2,2),(2,1),(2,0),(0,0)], [(2,2),(2,0),(1,0),(0,0)], [(2,2),(2,0),(0,0)].
Square array A(n,k) begins:
  1,  1,     1,        1,            1,                 1, ...
  1,  1,     3,        7,           25,               121, ...
  1,  2,    22,      248,         6506,            292442, ...
  1,  4,   188,    11380,      2359348,        1088626684, ...
  1,  8,  1712,   577124,    991365512,     4943064622568, ...
  1, 16, 16098, 30970588, 453530591824, 25162900228200976, ...
		

Crossrefs

Columns k=0-3 give: A000012, A011782, A132595(n+1), A229482.
Rows n=0-2 give: A000012, A038507 (for k>1), A229465.
Main diagonal gives: A229346.

Programs

  • Maple
    b:= proc(l) option remember; local m; m:= nops(l);
          `if`(m=0 or l[m]=0, 1,
          `if`(m>1, add(b(l-[j$m]), j=1..l[1]), 0)+
          add(add(b(sort(subsop(i=l[i]-j, l))), j=1..l[i]), i=1..m))
        end:
    A:= (n, k)-> b([n$k]):
    seq(seq(A(n, d-n), n=0..d), d=0..10);  # Alois P. Heinz, Sep 24 2013
  • Mathematica
    b[l_] := b[l] = With[{m = Length[l]}, If[m == 0 || l[[m]] == 0, 1, If[m > 1, Sum[b[l - Array[j&, m]], {j, 1, l[[1]]}],  0] + Sum[Sum[b[Sort[ReplacePart[l, i -> l[[i]] - j]]], {j, 1, l[[i]]}], {i, 1, m}]]]; a[n_, k_] := b[Array[n&, k]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Dec 16 2013, translated from Maple *)

A060774 a(n) = number of lattice paths from (0,0,0) to (n,n,n) along the cracks on the surface of a Rubik-ized n X n X n cube so that no step increases distance from goal.

Original entry on oeis.org

1, 6, 54, 384, 2550, 16506, 105840, 677088, 4335606, 27829230, 179161554, 1156987728, 7493841264, 48672149064, 316920674880, 2068273848384, 13525486999542, 88612412883030, 581503640659830, 3821691744347400, 25150239955660050, 165713382866931570
Offset: 0

Views

Author

Len Smiley, Apr 25 2001

Keywords

Comments

3-dimensional version of block-walking (0,0) to (n,n) in binomial(2n,n) ways.

Examples

			a(1)=6: XYZ, XZY, YXZ, YZX, ZXY, ZYX.
		

Crossrefs

Column k=3 of A225094.

Programs

  • Maple
    A060774 := proc(n)
            `if`(n=0, 1,
            6*(binomial(3*n,n)-binomial(2*n,n)) ) ;
    end proc: # R. J. Mathar, Oct 31 2015
  • Mathematica
    Rest[CoefficientList[Series[-(6/Sqrt[1-4z])+(12Cos[ArcCos[1-27z/2]/6])/Sqrt[4-27z], {z, 0, 20}], z]] (* Benedict W. J. Irwin, Jul 12 2016 *)
  • PARI
    j=[]; for(n=1,50,j=concat(j,6*(binomial(3*n,n)-binomial(2*n,n)))); j
    
  • PARI
    { for (n=1, 200, write("b060774.txt", n, " ", 6*(binomial(3*n, n) - binomial(2*n, n))); ) } \\ Harry J. Smith, Jul 11 2009

Formula

a(n) = 6*binomial(3n, n) - 6*binomial(2n, n).
a(n) = 6*A000846(n) for n>0. - R. J. Mathar, Oct 31 2015
Conjecture: 2*n*(2*n-1)*(n-1)*a(n) + (n-1)*(13*n^2-209*n+258)*a(n-1) + 2*(-259*n^3+1785*n^2-3728*n+2460)*a(n-2) + 6*(295*n^3-2068*n^2+4833*n-3780)*a(n-3) - 36*(3*n-10)*(2*n-7)*(3*n-11)*a(n-4) = 0. - R. J. Mathar, Oct 31 2015
Conjecture: 2*n*(n-1)*(2*n-1)*(11*n^2-33*n+24)*a(n) - (n-1)*(473*n^4-1892*n^3+2561*n^2-1338*n+216)*a(n-1) + 6*(3*n-5)*(3*n-4)*(2*n-3)*(11*n^2-11*n+2)*a(n-2) = 0. - R. J. Mathar, Oct 31 2015
From Benedict W. J. Irwin, Jul 12 2016: (Start)
G.f.: -6/sqrt(1-4*x) + 12*cos(arccos(1-27*x/2)/6)/sqrt(4-27*x).
E.g.f: -6*E^(2*x)*BesselI(0,2*x) + 6*2F2(1/3,2/3;1/2,1;27*x/4).
(End)
a(n) ~ 4^(-n)*(3^(3*n+3/2))/sqrt(Pi*n). - Ilya Gutkovskiy, Jul 12 2016

Extensions

Corrected by Franklin T. Adams-Watters and T. D. Noe, Oct 25 2006
a(0)=1 prepended by Alois P. Heinz, Sep 09 2016

A071798 Number of paths on the surface of the n-dimensional lattice [0..2]^n; i.e., the lattice paths that do not pass through the point (1,1,...,1).

Original entry on oeis.org

0, 2, 54, 1944, 99000, 6966000, 655678800, 80103945600, 12372954249600, 2362712677920000, 547235129437920000, 151247218046601600000, 49191138900262719360000, 18601307697723249058560000, 8093164859945489259936000000, 4014620173473616480790016000000
Offset: 1

Views

Author

T. D. Noe, Jun 06 2002

Keywords

Comments

a(2) + 1 = 3 is prime. a(3) - 1 = 53 is prime. a(5) - 1 = 98999 is prime. a(7) + 1 = 655678801 is prime. a(8) - 1 = 80103945599 is prime, and part of a twin prime, as a(8) + 1 = 80103945601 is prime. a(13) - 1 = 49191138900262719359999 is prime. - Jonathan Vos Post, Sep 01 2009

Crossrefs

Cf. A000680.
Row n=2 of A225094. - Alois P. Heinz, Apr 27 2013

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<3, (n-1)*n,
           n*((3*n^2-7*n+3)*a(n-1)-(2*n-3)*(n-1)^3*a(n-2))/(n-2))
        end:
    seq(a(n), n=1..20);  # Alois P. Heinz, Apr 26 2013
  • Mathematica
    Table[(2n)!/2^n-(n!)^2, {n, 10}]

Formula

a(n) = (2n)!/2^n - (n!)^2.

Extensions

More terms from Harvey P. Dale, May 26 2011

A225096 Number of lattice paths without interior points from {3}^n to {0}^n using steps that decrement one component by 1.

Original entry on oeis.org

1, 0, 2, 384, 132000, 79716000, 78928416000, 120481708032000, 269702267433984000, 850271305403520000000, 3652393464869909760000000, 20798525597035736309760000000, 153427251286862484058423296000000, 1437639344607855309441929920512000000
Offset: 0

Views

Author

Alois P. Heinz, Apr 27 2013

Keywords

Comments

An interior point p = (p_1, ..., p_n) has n>0 components with 0

Examples

			a(0) = 1: [()].
a(1) = 0, there is no path from (3) to (0) without interior points.
a(2) = 2: [(3,3), (2,3), (1,3), (0,3), (0,2), (0,1), (0,0)], [(3,3), (3,2), (3,1), (3,0), (2,0), (1,0), (0,0)].
		

Crossrefs

Row n=3 of A225094.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<3, [1, 0, 2][n+1],
           (2*(3*n-1)*(3*n-2)*(7*n^2-9*n-4)*n*a(n-1)
           -3*n^2*(3*n-5)*(3*n-1)*(3*n-4)*(3*n-2)*(n-1)^2*a(n-2))/
           (8*(2*n+1)*(n-2)))
        end:
    seq(a(n), n=0..20);

A225111 Number of lattice paths without interior points from {n}^n to {0}^n using steps that decrement one component by 1.

Original entry on oeis.org

1, 1, 2, 384, 8059800, 38606650125120, 71646205399259162031360, 78385944219935192681549282987212800, 71605824043564034004713155518007394441060661360000, 73473023853389304132357517396557811159635782691183541179936000000000
Offset: 0

Author

Alois P. Heinz, Apr 28 2013

Keywords

Comments

An interior point p = (p_1, ..., p_n) has n>0 components with 0

Crossrefs

Main diagonal of A225094.

Programs

  • Maple
    b:= proc(n, l) option remember; local m; m:= nops(l);
          `if`(m=0 or l[m]=0, 1, `if`(l[1]>0 and l[m] b(n, [n$n]):
    seq(a(n), n=0..9);
  • Mathematica
    b[n_, l_] := b[n, l] = With[{m = Length[l]}, If[m == 0 || l[[m]] == 0, 1,
         If[l[[1]] > 0 && l[[m]] < n, 0, Sum[If[l[[i]] == 0, 0, b[n, Sort[
         ReplacePart[l, i -> l[[i]] - 1]]]], {i, 1, m}]]]];
    a[n_] := b[n, Array[n&, n]];
    Table[a[n], {n, 0, 9}] (* Jean-François Alcover, Apr 28 2022, after Alois P. Heinz *)
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