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 1-9 of 9 results.

A181197 Number of 3 X n matrices containing a permutation of 1..3*n in increasing order rowwise, columnwise and (downwards) antidiagonally.

Original entry on oeis.org

1, 1, 4, 29, 290, 3532, 49100, 750325, 12310294, 213446666, 3868253164, 72686739116, 1407643591804, 27964937748724, 567853691242796, 11751537336221989, 247263499985110046, 5279409371079693454, 114199628255736623996, 2499214354674134770354
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Row 3 of A181196.
Equivalently, the number of "truncated shifted standard Young tableaux" of shape ; in other words, if we shift the middle row to the right by one unit and the bottom row to the right by two units, we require that the resulting diagram be increasing as we read down or to the right.
To count these tableaux, observe that if we put the entry 2n + 2 + k in the last position of the second row, the bottom row must end with the entries 2n + 3 + k, ..., 3n. The remaining figure can be filled in arbitrarily; it is a shifted Young diagram of shape . Now apply the hook-length formula for shifted Young tableaux. (This argument is due to Greta Panova.)
a(n) is also the number of maximum packings of pattern
[5 6]
[3 4]
[1 2] in column-strict arrays of size 3 X n+1. - Ran Pan, Apr 13 2015
a(n) is also the number of standard Young tableaux of shape (n,n,n) (French notation) such that for any element T(i,j) in the tableau T, its upper element T(i+1,j) is larger than its right element T(i,j+1). - Ran Pan, Apr 13 2015

Examples

			All four 3 X 3 examples:
1..2..3....1..2..3....1..2..4....1..2..4
4..5..6....4..5..7....3..5..6....3..5..7
7..8..9....6..8..9....7..8..9....6..8..9
		

Crossrefs

Row n=3 of A227578. - Alois P. Heinz, Jul 17 2013

Programs

  • Maple
    a:= n-> `if`(n<2, 1, add(((2*n+k-1)!*(n-k)*(n-k-1)) /
             (n!*(n-1)!*k!*(2*n-1)*(n+k)*(n+k-1)), k=0..n-2)):
    seq(a(n), n=1..30);  # Alois P. Heinz, Jul 01 2012
  • Mathematica
    Flatten[{1,Table[Sum[((2*n+k-1)!*(n-k)*(n-k-1))/(n!*(n-1)!*k!*(2*n-1)*(n+k)*(n+k-1)),{k,0,n-2}],{n,2,20}]}] (* Vaclav Kotesovec, Jul 21 2013 *)

Formula

a(n) = Sum_{k=0..n-2} ((2n+k-1)!*(n-k)*(n-k-1)) / (n!*(n-1)!*k!*(2n-1) * (n+k)*(n+k-1)) for n>=2, a(1) = 1.
Recurrence: (2*n-1)*(7*n-13)*n^2*a(n) = 2*(182*n^4 - 1185*n^3 + 2722*n^2 - 2625*n + 900)*a(n-1) + 3*(2*n-5)*(3*n-5)*(3*n-4)*(7*n-6)*a(n-2). - Vaclav Kotesovec, Jul 21 2013
a(n) ~ 3^(3*n+1/2)/(64*Pi*n^4). - Vaclav Kotesovec, Jul 21 2013

Extensions

Formula and comments from Joel B. Lewis, Jul 25 2011

A227578 Number A(n,k) of lattice paths from {n}^k to {0}^k using steps that decrement one component such that for each point (p_1,p_2,...,p_k) we have p_1<=p_2<=...<=p_k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 4, 1, 1, 1, 14, 29, 8, 1, 1, 1, 42, 290, 185, 16, 1, 1, 1, 132, 3532, 7680, 1257, 32, 1, 1, 1, 429, 49100, 456033, 238636, 8925, 64, 1, 1, 1, 1430, 750325, 34426812, 77767945, 8285506, 65445, 128, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 16 2013

Keywords

Comments

Conjecture: column k is asymptotic to c(k) * (k+1)^(k*n)/n^((k^2-1)/2), where c(k) is a constant dependent only on k. - Vaclav Kotesovec, Jul 21 2013

Examples

			A(4,0) = 1: [()].
A(3,1) = 4: [(3),(0)], [(3),(1),(0)], [(3),(2),(0)], [(3),(2),(1),(0)].
A(2,2) = 5: [(2,2),(0,2),(0,0)], [(2,2),(0,2),(0,1),(0,0)], [(2,2),(1,2),(0,2),(0,0)], [(2,2),(1,2),(0,2),(0,1),(0,0)], [(2,2),(1,2),(1,1),(0,1),(0,0)].
A(1,3) = 1: [(1,1,1),(0,1,1),(0,0,1),(0,0,0)].
A(0,4) = 1: [(0,0,0,0)].
Square array A(n,k) begins:
  1,  1,    1,      1,        1,           1, ...
  1,  1,    1,      1,        1,           1, ...
  1,  2,    5,     14,       42,         132, ...
  1,  4,   29,    290,     3532,       49100, ...
  1,  8,  185,   7680,   456033,    34426812, ...
  1, 16, 1257, 238636, 77767945, 36470203156, ...
		

Crossrefs

Rows n=0+1, 2-10 give: A000012, A000108(k+1), A181197(k+2), A227584, A227602, A227603, A227604, A227605, A227606, A227607.
Main diagonal gives: A227579.
Cf. A060854 (steps decrement one component by 1), A262809, A263159.
A181196 is a similar but different array.

Programs

  • Maple
    b:= proc(l) option remember; `if`(l[-1]=0, 1, add(add(b(subsop(
          i=j, l)), j=`if`(i=1, 0, l[i-1])..l[i]-1), i=1..nops(l)))
        end:
    A:= (n, k)-> `if`(k=0, 1, b([n$k])):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    b[l_] := b[l] = If[ l[[-1]] == 0, 1, Sum[ Sum[ b[ReplacePart[l, i -> j]], {j, If[i == 1, 0, l[[i-1]]], l[[i]]-1}], {i, 1, Length[l]}]]; a[n_, k_] := If[k == 0, 1, b[Array[n&, k]]]; Table[Table[a[n, d - n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Dec 09 2013, translated from Maple *)

A181191 Number of n X n matrices containing a permutation of 1..n*n in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 1, 4, 169, 141696, 3777546912, 4673805856338368, 368253691037579094795185, 2426023001499238992505630883146240, 1697356437632520242875237327471631991584394752, 156101219875805260212264222801658705937606174957553142873088
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Examples

			All solutions for 3 X 3:
..1..2..3....1..2..3....1..2..4....1..2..4
..4..5..6....4..5..7....3..5..6....3..5..7
..7..8..9....6..8..9....7..8..9....6..8..9
		

Crossrefs

Main diagonal of A181196.

Programs

  • Maple
    b:= proc(l) option remember; local n; n:= nops(l);
          `if`({l[]}={0}, 1, add(`if`((i=1 or l[i-1]<=l[i]) and l[i]>
          `if`(i=n, 0, l[i+1]), b(subsop(i=l[i]-1, l)), 0), i=1..n))
        end:
    a:= n-> b([n$n]):
    seq(a(n), n=1..10);  # Alois P. Heinz, Jul 24 2012
  • Mathematica
    b[l_] := b[l] = With[{n = Length[l]},
       If[Union[l]=={0}, 1, Sum[If[(i==1 || l[[i-1]] <= l[[i]]) && l[[i]] >
       If[i==n, 0, l[[i+1]]], b[ReplacePart[l, i->l[[i]]-1]], 0], {i, 1, n}]]];
    a[n_] := b[Table[n, {n}]];
    Table[a[n], {n, 1, 11}] (* Jean-François Alcover, May 10 2022, after Alois P. Heinz *)

Extensions

a(10)-a(16) from Alois P. Heinz, Jul 24 2012

A181192 Number of n X 5 matrices containing a permutation of 1..n*5 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 14, 290, 6392, 141696, 3142704, 69705920, 1546100352, 34293030016, 760631058944, 16871055411200, 374205743270912, 8300010573582336, 184097055591849984, 4083335265314938880, 90569764059295875072
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 5 of A181196.

Examples

			Some solutions for 4 X 5:
..1..2..3..4..5....1..2..3..4..5....1..2..3..4..5....1..2..3..4..5
..6..7..8..9.10....6..7..8..9.10....6..7..8..9.10....6..7..8..9.10
.11.12.13.14.15...11.12.13.14.17...11.12.13.14.16...11.12.13.14.18
.16.17.18.19.20...15.16.18.19.20...15.17.18.19.20...15.16.17.19.20
		

Crossrefs

Cf. A181196.

Formula

Empirical: a(n) = 24*a(n-1) - 40*a(n-2) - 8*a(n-3).
Conjectures from Colin Barker, Feb 27 2018: (Start)
G.f.: x*(1 - 10*x - 6*x^2) / ((1 - 2*x)*(1 - 22*x - 4*x^2)).
a(n) = 2^(n-2) + ((11-5*sqrt(5))^n*(2+sqrt(5)) + (-2+sqrt(5))*(11+5*sqrt(5))^n) / (4*sqrt(5)).
(End)

A181193 Number of n X 6 matrices containing a permutation of 1..n*6 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 42, 3532, 352184, 36372976, 3777546912, 392658046912, 40820345224064, 4243729567634176, 441184342397471232, 45866192670977108992, 4768319236090599225344, 495721734753595527294976
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 6 of A181196.

Examples

			Some solutions for 4 X 6:
..1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6
..7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12
.13.14.15.16.17.18...13.14.15.17.19.20...13.14.15.17.19.21...13.14.15.17.19.22
.19.20.21.22.23.24...16.18.21.22.23.24...16.18.20.22.23.24...16.18.20.21.23.24
		

Crossrefs

Cf. A181196.

Formula

Empirical: a(n) = 120*a(n-1) - 1672*a(n-2) + 544*a(n-3) - 6672*a(n-4) + 256*a(n-5).
Empirical g.f.: x*(1 - 78*x + 164*x^2 - 1976*x^3 + 224*x^4) / ((1 - 16*x)*(1 - 104*x + 4*x^2)*(1 + 4*x^2)). - Colin Barker, Feb 27 2018

A181194 Number of n X 7 matrices containing a permutation of 1..n*7 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 132, 49100, 25097600, 14083834704, 8092149471168, 4673805856338368, 2702482348019033600, 1562998915785444034816, 904016986809953084011520, 522876616523380188491377664, 302428597238403007787949047808
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 7 of A181196.

Examples

			Some solutions for 4 X 7:
..1..2..3..4..5..6..7....1..2..3..4..5..7.10....1..2..3..4..5..7.10
..8..9.10.11.12.13.14....6..8..9.12.13.15.19....6..8..9.12.13.15.19
.15.16.17.18.19.20.21...11.14.17.18.20.22.24...11.14.17.18.20.22.25
.22.23.24.25.26.27.28...16.21.23.25.26.27.28...16.21.23.24.26.27.28
		

Crossrefs

Cf. A181196.

Formula

Empirical: a(n) = 720*a(n-1) - 84448*a(n-2) + 1503360*a(n-3) - 17912224*a(n-4) - 318223104*a(n-5) + 564996096*a(n-6) + 270471168*a(n-7) - 11373824*a(n-8) + 65536*a(n-9).
Empirical g.f.: x*(1 - 588*x + 38508*x^2 - 610624*x^3 - 20571792*x^4 + 98269760*x^5 + 112896832*x^6 - 6488576*x^7 + 57344*x^8) / ((1 - 2*x)*(1 - 26*x + 512*x^2)*(1 - 114*x - 1156*x^2 + 8*x^3)*(1 - 578*x - 228*x^2 + 8*x^3)). - Colin Barker, Feb 27 2018

A181195 Number of n X 8 matrices containing a permutation of 1..n*8 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 429, 750325, 2152061145, 7372392431849, 26791156423752069, 99086837728795943389, 368253691037579094795185, 1370391973012218579798432209, 5101453317266742158652901045085
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 8 of A181196.

Examples

			Some solutions for 3 X 8:
..1..2..3..4..5..6..7..8....1..2..3..4..5..6..7.11....1..2..3..4..5..6..7.11
..9.10.11.12.13.14.15.16....8..9.10.12.13.16.17.19....8..9.10.12.13.16.17.20
.17.18.19.20.21.22.23.24...14.15.18.20.21.22.23.24...14.15.18.19.21.22.23.24
		

Crossrefs

Cf. A181196.

A181198 Number of 4 X n matrices containing a permutation of 1..4*n in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 1, 8, 169, 6392, 352184, 25097600, 2152061145, 212012802584, 23263015359672, 2781709560836960, 356806123331844056, 48516442013911012288, 6930091952294051922080, 1032505514388962439665280, 159544871422153344631037625, 25451354639006231998529405016
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Examples

			Some solutions for 4 X 4:
   1  2  3  4    1  2  3  4    1  2  3  4    1  2  3  4    1  2  3  4
   5  6  7  8    5  6  7  8    5  6  7  8    5  6  7  8    5  6  7  8
   9 10 11 12    9 10 11 13    9 10 11 14    9 10 12 13    9 10 12 14
  13 14 15 16   12 14 15 16   12 13 15 16   11 14 15 16   11 13 15 16
		

Crossrefs

Row 4 of A181196.

Programs

  • Mathematica
    Table[
     NextPartitions[n1_, n2_, n3_, n4_] :=
       If[n1 < n, f[n1 + 1, n2, n3, n4], 0] +
       If[n2 < n1 - 1 || n2 === n - 1, f[n1, n2 + 1, n3, n4], 0] +
       If[n3 < n2 - 1 || n3 === n - 1 === n2 - 1, f[n1, n2, n3 + 1, n4], 0] +
       If[n4 < n3 - 1, f[n1, n2, n3, n4 + 1], 0];
     pp = f[1, 0, 0, 0];
     Do[pp = Expand[pp /. f[ns__] :> NextPartitions[ns]], {4 n - 2}];
     pp /. f[n, n, n, n - 1] -> 1,
    {n, 20}] (* Christoph Koutschan, Feb 26 2023 *)

Formula

Conjectured recurrence of order 2 and degree 9: 3*(n + 1)*(2*n + 3)*(3*n + 4)*(3*n + 5)*(7*n^2 - 1)*(n + 2)^3*a(n + 2) - 8*(n + 1)*(2*n + 1)*(4*n + 3)*(4*n + 5)*(364*n^5 + 84*n^4 - 1025*n^3 - 534*n^2 + 157*n + 54)*a(n + 1) - 64*(2*n - 1)^2*(2*n + 1)*(4*n - 1)*(4*n + 1)*(4*n + 3)*(4*n + 5)*(7*n^2 + 14*n + 6)*a(n) = 0. - Christoph Koutschan, Feb 26 2023
Conjectured formula, solution to the above recurrence, for n > 1: a(n) = (-64)^n * (n-1) * (-1/2){2*n} * (1/2){n} / (4*(3*n)!) * (-1 + 3*Sum_{k=2..n-1} (-4)^k * (7*k^2-1) / ((k-1) * k * (k+1)^2 * (2*k-1)^2 * (2*k+1)^3) * binomial(3*k,2*k) * binomial(k+1/2,k)), where (a)_{n} is the Pochhammer symbol.

Extensions

a(12)-a(27) from Alois P. Heinz, Jul 24 2012
a(28)-a(100) from Christoph Koutschan, Feb 26 2023

A181199 Number of 5 X n matrices containing a permutation of 1..5*n in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally.

Original entry on oeis.org

1, 1, 16, 985, 141696, 36372976, 14083834704, 7372392431849, 4848332563899256, 3808369342900073856, 3447336241467721584256, 3503140094024746011745456, 3918646197894288330216058576, 4753102567048482059557067412816, 6178133154985813161258658378449616
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Examples

			Some solutions for 5 X 4:
  1  2  3  4    1  2  3  4    1  2  3  4    1  2  3  4    1  2  3  4
  5  6  7  8    5  6  7  8    5  6  7  8    5  6  7  8    5  6  7  8
  9 10 11 12    9 10 11 12    9 10 11 12    9 10 11 12    9 10 11 12
 13 14 15 16   13 14 15 17   13 14 15 18   13 14 16 17   13 14 16 18
 17 18 19 20   16 18 19 20   16 17 19 20   15 18 19 20   15 17 19 20
		

Crossrefs

Row 5 of A181196.

Programs

  • Mathematica
    Table[
      NextPartitions[n1_, n2_, n3_, n4_, n5_] :=
        If[n1 < n, f[n1 + 1, n2, n3, n4, n5], 0] +
        If[n2 < n1 - 1 || n2 === n - 1, f[n1, n2 + 1, n3, n4, n5], 0] +
        If[n3 < n2 - 1 || n3 === n - 1 === n2 - 1, f[n1, n2, n3 + 1, n4, n5], 0] +
        If[n4 < n3 - 1 || n4 === n - 1 === n3 - 1, f[n1, n2, n3, n4 + 1, n5], 0] +
        If[n5 < n4 - 1, f[n1, n2, n3, n4, n5 + 1], 0];
      pp = f[1, 0, 0, 0, 0];
      Do[pp = Expand[pp /. f[ns__] :> NextPartitions[ns]], {5 n - 2}];
      pp /. f[n, n, n, n, n - 1] -> 1,
    {n, 20}] (* Christoph Koutschan, Feb 27 2023 *)

Formula

Conjectured recurrence of order 3 and degree 24: 3*(n + 2)^2*(2*n + 3)*(2*n + 5)^2*(3*n + 7)*(3*n + 8)*(4*n + 9)*(4*n + 11)*(137855872*n^11 + 860969696*n^10 + 2047036856*n^9 + 2032587274*n^8 - 24192441*n^7 - 1894061166*n^6 - 1671661480*n^5 - 524330624*n^4 + 36004789*n^3 + 62751860*n^2 + 13865604*n + 927360)*(n + 3)^4*a(n + 3) - (n + 2)^2*(2*n + 3)*(717088749346816*n^21 + 14962008250398720*n^20 + 139665528127686656*n^19 + 760770273998231808*n^18 + 2616700630350746208*n^17 + 5556799141672247640*n^16 + 5462710847171622988*n^15 - 6080171043591548610*n^14 - 31771892184486994333*n^13 - 54791308745183340309*n^12 - 46634308960957698567*n^11 - 1215620047630796049*n^10 + 48833460779191449763*n^9 + 65692918122110754573*n^8 + 47097079083848116511*n^7 + 19628106098287909191*n^6 + 3499276436019940446*n^5 - 850259283025327524*n^4 - 685802053101717288*n^3 - 180089041888657440*n^2 - 22603977271411200*n - 1104708217536000)*a(n + 2) - 15*(2*n + 1)*(5*n + 6)*(5*n + 7)*(5*n + 8)*(5*n + 9)*(9113927409664*n^19 + 166164038596608*n^18 + 1357324488921088*n^17 + 6541981632511232*n^16 + 20586994844739808*n^15 + 44061606220301336*n^14 + 64302800289940820*n^13 + 61042725728660150*n^12 + 30740208891967721*n^11 - 3351043407516635*n^10 - 17410620603191989*n^9 - 12634296322883951*n^8 - 4487751704725767*n^7 - 793918042456325*n^6 - 54713722756179*n^5 + 42448206362469*n^4 + 50327965592874*n^3 + 21777752002716*n^2 + 4014999151560*n + 257403484800)*a(n + 1) + 25*(2*n - 1)^2*(2*n + 1)*(4*n - 1)*(4*n + 1)*(5*n + 1)*(5*n + 2)*(5*n + 3)*(5*n + 4)*(5*n + 6)*(5*n + 7)*(5*n + 8)*(5*n + 9)*(137855872*n^11 + 2377384288*n^10 + 18238806776*n^9 + 81945774178*n^8 + 238738633847*n^7 + 471293180347*n^6 + 638861237719*n^5 + 588363536007*n^4 + 354332674386*n^3 + 128320688700*n^2 + 23068181160*n + 1077753600)*a(n) = 0. - Christoph Koutschan, Feb 27 2023
Conjecture: a(n) ~ 9 * 5^(5*n + 1/2) / (2^17 * Pi^2 * n^12), based on the recurrence by Christoph Koutschan. - Vaclav Kotesovec, Feb 27 2023

Extensions

a(11)-a(26) from Alois P. Heinz, Jul 24 2012
Showing 1-9 of 9 results.