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 29 results. Next

A052397 Duplicate of A047889.

Original entry on oeis.org

1, 2, 6, 24, 119, 694, 4582, 33324, 261808, 2190688, 19318688, 178108704
Offset: 0

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Author

Keywords

A116485 Number of permutations in S_n that avoid the pattern 12453 (or equivalently, 31245).

Original entry on oeis.org

1, 1, 2, 6, 24, 119, 694, 4581, 33286, 260927, 2174398, 19053058, 174094868, 1648198050, 16085475576, 161174636600, 1652590573612, 17292601075489, 184246699159418, 1995064785620557, 21919480341617102, 244015986016996763, 2749174129340156922, 31313478171012371344
Offset: 0

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Author

Zvezdelina Stankova (stankova(AT)mills.edu), Mar 19 2006

Keywords

Comments

a(n) is also the number of permutations in S_n that avoid the pattern 21453 or any of its symmetries. The Wilf class consists of 16 permutations. - David Bevan, Jun 17 2021

Crossrefs

Representatives for the 16 Wilf-equivalence patterns of length 5 are given in A116485, A047889, and A256195-A256208. - N. J. A. Sloane, Mar 19 2015

Programs

  • Mathematica
    avoid[n_, pat_] := Module[{p1 = pat[[1]], p2 = pat[[2]], p3 = pat[[3]], p4 = pat[[4]], p5 = pat[[5]], lseq = {}, i, p,
        lpat = Subsets[(n + 1) - Range[n], {Length[pat]}],
        psn = Permutations[Range[n]]},
       For[i = 1, i <= Length[lpat], i++,
        p = lpat[[i]];
        AppendTo[lseq, Select[psn, MemberQ[#, {_, p[[p1]], _, p[[p2]], _, p[[p3]], _, p[[p4]], _, p[[p5]], _}, {0}] &]];
        ]; n! - Length[Union[Flatten[lseq, 1]]]];
    Table[avoid[n, {1, 2, 4, 5, 3}], {n, 0, 8}]  (* Robert Price, Mar 27 2020 *)

Formula

Conjecture: a(n) + A158423(n) = n!. - Benedict W. J. Irwin, Mar 15 2016
The conjecture is true: All that is needed is to show that 23145 is Wilf-equivalent to 31245, but that’s obvious since they are inverses. - Doron Zeilberger and Yonah Biers-Ariel, Feb 26 2019
The exponential growth rate is 9+4*sqrt(2). See [Bona 2004]. - David Bevan, Jun 17 2021

Extensions

More terms from the Zvezdelina Stankova-Frenkel and Julian West paper. - N. J. A. Sloane, Mar 19 2015
More terms from Doron Zeilberger and Yonah Biers-Ariel, Feb 26 2019
More terms from Yonah Biers-Ariel, Mar 04 2019

A214015 Number of permutations A(n,k) in S_n with longest increasing subsequence of length <= k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 1, 0, 1, 1, 2, 5, 1, 0, 1, 1, 2, 6, 14, 1, 0, 1, 1, 2, 6, 23, 42, 1, 0, 1, 1, 2, 6, 24, 103, 132, 1, 0, 1, 1, 2, 6, 24, 119, 513, 429, 1, 0, 1, 1, 2, 6, 24, 120, 694, 2761, 1430, 1, 0, 1, 1, 2, 6, 24, 120, 719, 4582, 15767, 4862, 1, 0
Offset: 0

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Author

Alois P. Heinz, Jul 01 2012

Keywords

Comments

A(n,k) is also the sum of the squares of numbers of standard Young tableaux (SYT) of height <= k over all partitions of n.
This array is a larger and reflected version of A047888.
Column k>1 is asymptotic to (Product_{j=1..k} j!) * k^(2*n + k^2/2) / (Pi^((k-1)/2) * 2^((k-1)*(k+2)/2) * n^((k^2-1)/2)). - Vaclav Kotesovec, Sep 10 2014

Examples

			A(4,2) = 14 because 14 permutations of {1,2,3,4} do not contain an increasing subsequence of length > 2: 1432, 2143, 2413, 2431, 3142, 3214, 3241, 3412, 3421, 4132, 4213, 4231, 4312, 4321.  Permutation 1423 is not counted because it contains the noncontiguous increasing subsequence 123.
A(4,2) = 14 = 2^2 + 3^2 + 1^2 because the partitions of 4 with <= 2 parts are [2,2], [3,1], [4] with 2, 3, 1 standard Young tableaux, respectively:
  +------+  +------+  +---------+  +---------+  +---------+  +------------+
  | 1  3 |  | 1  2 |  | 1  3  4 |  | 1  2  4 |  | 1  2  3 |  | 1  2  3  4 |
  | 2  4 |  | 3  4 |  | 2 .-----+  | 3 .-----+  | 4 .-----+  +------------+
  +------+  +------+  +---+        +---+        +---+
Square array A(n,k) begins:
  1,  1,   1,    1,    1,    1,    1,    1, ...
  0,  1,   1,    1,    1,    1,    1,    1, ...
  0,  1,   2,    2,    2,    2,    2,    2, ...
  0,  1,   5,    6,    6,    6,    6,    6, ...
  0,  1,  14,   23,   24,   24,   24,   24, ...
  0,  1,  42,  103,  119,  120,  120,  120, ...
  0,  1, 132,  513,  694,  719,  720,  720, ...
  0,  1, 429, 2761, 4582, 5003, 5039, 5040, ...
		

Crossrefs

Differences between A000142 and columns k=0-9 give: A000142 (for n>0), A033312, A056986, A158005, A158432, A159139, A159175, A217675, A217676, A217677.
Main diagonal and first lower diagonal give: A000142, A033312.
A(2n,n-1) gives A269042(n) for n>0.

Programs

  • Maple
    h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j
          +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
        end:
    g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
                     add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
    A:= (n, k)-> `if`(k>=n, n!, g(n, k, [])):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]! / Product[Product[1+l[[i]]-j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
    g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]];
    A[n_, k_] := If[k >= n, n!, g[n, k, {}]];
    Table [Table [A[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 09 2013, translated from Maple *)

A099952 Number of Wilf classes in S_n.

Original entry on oeis.org

1, 1, 1, 3, 16, 91, 595
Offset: 1

Views

Author

N. J. A. Sloane, Nov 12 2004

Keywords

References

  • Z. Stankova and J. West, A new class of Wilf-equivalent permutations, J. Algeb. Combin., 15 (2002), 271-290.

Crossrefs

Representatives for the three Wilf classes in S_4 are A005802, A022558, A061552. - N. J. A. Sloane, Mar 15 2015
Representatives for the 16 Wilf-equivalence patterns of length 5 are given in A116485, A047889, and A256195-A256208. - N. J. A. Sloane, Mar 19 2015

A256195 Number of permutations in S_n that avoid the pattern 25314.

Original entry on oeis.org

1, 1, 2, 6, 24, 119, 694, 4578, 33184, 258757, 2136978, 18478134, 165857600, 1535336290, 14584260700, 141603589300, 1400942032152, 14087464765300, 143689133196008, 1484090443264936, 15499968503875136, 163501005435759505, 1740170514634463426, 18671118911254798454
Offset: 0

Views

Author

N. J. A. Sloane, Mar 19 2015

Keywords

Crossrefs

Representatives for the 16 Wilf-equivalence patterns of length 5 are given in A116485, A047889, and A256195-A256208.
Cf. A099952.

Programs

  • Mathematica
    avoid[n_, pat_] := Module[{p1 = pat[[1]], p2 = pat[[2]], p3 = pat[[3]], p4 = pat[[4]], p5 = pat[[5]], lseq = {}, i, p,
        lpat = Subsets[(n + 1) - Range[n], {Length[pat]}],
        psn = Permutations[Range[n]]},
       For[i = 1, i <= Length[lpat], i++,
        p = lpat[[i]];
        AppendTo[lseq, Select[psn, MemberQ[#, {_, p[[p1]], _, p[[p2]], _, p[[p3]], _, p[[p4]], _, p[[p5]], _}, {0}] &]];
        ]; n! - Length[Union[Flatten[lseq, 1]]]];
    Table[avoid[n, {2, 5, 3, 1, 4}], {n, 0, 8}]  (* Robert Price, Mar 27 2020 *)

Extensions

a(14)-a(16) from Bert Dobbelaere, Mar 18 2021
More terms from Anthony Guttmann, Sep 29 2021

A256208 Number of permutations in S_n that avoid the pattern 52341.

Original entry on oeis.org

1, 1, 2, 6, 24, 119, 694, 4582, 33325, 261863, 2192390, 19358590, 178904675, 1720317763, 17132629082, 176055309619, 1861037944163, 20185165186517, 224150069984572, 2543698932578158, 29451619807433107, 347417296695040510, 4170088041714300134, 50874753262007210667
Offset: 0

Views

Author

N. J. A. Sloane, Mar 19 2015

Keywords

Crossrefs

Representatives for the 16 Wilf-equivalence patterns of length 5 are given in A116485, A047889, and A256195-A256208.
Cf. A099952.

Programs

  • Mathematica
    avoid[n_, pat_] := Module[{p1 = pat[[1]], p2 = pat[[2]], p3 = pat[[3]], p4 = pat[[4]], p5 = pat[[5]], lseq = {}, i, p,
        lpat = Subsets[(n + 1) - Range[n], {Length[pat]}],
        psn = Permutations[Range[n]]},
       For[i = 1, i <= Length[lpat], i++,
        p = lpat[[i]];
        AppendTo[lseq, Select[psn, MemberQ[#, {_, p[[p1]], _, p[[p2]], _, p[[p3]], _, p[[p4]], _, p[[p5]], _}, {0}] &]];
        ]; n! - Length[Union[Flatten[lseq, 1]]]];
    Table[avoid[n, {5, 2, 3, 4, 1}], {n, 0, 8}]  (* Robert Price, Mar 27 2020 *)

Extensions

More terms from Anthony Guttmann, Sep 29 2021

A052399 Number of permutations in S_n with longest increasing subsequence of length <= 6.

Original entry on oeis.org

1, 1, 2, 6, 24, 120, 720, 5039, 40270, 361302, 3587916, 38957991, 457647966, 5763075506, 77182248916, 1091842643475, 16219884281650, 251774983140578, 4066273930979460, 68077194367392864, 1177729684507324152, 20995515989327134152, 384762410996641402384
Offset: 0

Views

Author

N. J. A. Sloane, Mar 13 2000

Keywords

Comments

Previous name was: Related to Young tableaux of bounded height.

Crossrefs

Column k=6 of A214015.

Programs

  • Maple
    h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j
           +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
        end:
    g:= proc(n, i, l) option remember;
          `if`(n=0, h(l)^2, `if`(i<1, 0, `if`(i=1, h([l[], 1$n])^2,
           g(n, i-1, l)+ `if`(i>n, 0, g(n-i, i, [l[], i])))))
        end:
    a:= n-> g(n, 6, []):
    seq(a(n), n=0..25); # Alois P. Heinz, Apr 10 2012
    # second Maple program
    a:= proc(n) option remember; `if`(n<7, n!,
          ((56*n^5-9408+11032*n+19028*n^2+7360*n^3+1092*n^4)*a(n-1)
           -4*(196*n^3+1608*n^2+3167*n+444)*(n-1)^2*a(n-2)
           +1152*(2*n+3)*(n-1)^2*(n-2)^2*a(n-3))/ ((n+9)*(n+8)^2*(n+5)^2))
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Sep 26 2012
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1+l[[i]]-j+Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_, k_] := If[k >= n, n!, g[n, k, {}]]; Table[a[n, 6], {n, 0, 30}] (* Jean-François Alcover, Mar 11 2014, after Alois P. Heinz *)

Formula

a(n) ~ 5 * 2^(2*n + 6) * 3^(2*n + 21) / (n^(35/2) * Pi^(5/2)). - Vaclav Kotesovec, Sep 10 2014

Extensions

More terms from Alois P. Heinz, Apr 10 2012
New name from Vaclav Kotesovec, Sep 10 2014

A072131 T_7(n) in the notation of Bergeron et al., u_k(n) in the notation of Gessel: Related to Young tableaux of bounded height.

Original entry on oeis.org

1, 2, 6, 24, 120, 720, 5040, 40319, 362815, 3626197, 39832877, 476591309, 6162155981, 85494566892, 1264755621000, 19835792076675, 328115505900675, 5698062006852574, 103455252673577866, 1956590161853191160, 38418713005615268760, 780931481835878011620
Offset: 1

Views

Author

Jesse Carlsson (j.carlsson(AT)physics.unimelb.edu.au), Jun 25 2002

Keywords

Crossrefs

Cf. A052399 for T_6(n), A047890 for T_5(n), A047889 for T_4(n).
Column k=7 of A214015.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<8, n!, ((-343035+429858*n
           +238440*n^3+38958*n^4+634756*n^2+2940*n^5+84*n^6)*a(n-1)
           -(1974*n^4+36336*n^3+213240*n^2+407840*n+82425)*(n-1)^2*a(n-2)
           +2*(49875+42646*n+6458*n^2)*(n-1)^2*(n-2)^2*a(n-3)
           -11025*(n-1)^2*(n-2)^2*(n-3)^2*a(n-4))/ ((n+6)^2*(n+10)^2*(n+12)^2))
        end:
    seq (a(n), n=1..30);  # Alois P. Heinz, Sep 26 2012
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 7, n!, g[n, 7, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)

Formula

a(n) ~ 6075 * 7^(2*n + 49/2) / (32768 * n^24 * Pi^3). - Vaclav Kotesovec, Sep 10 2014

Extensions

Typo in title corrected by Joel B. Lewis, Jul 16 2009

A072132 T_8(n) in the notation of Bergeron et al., u_k(n) in the notation of Gessel: Related to Young tableaux of bounded height.

Original entry on oeis.org

1, 2, 6, 24, 120, 720, 5040, 40320, 362879, 3628718, 39912738, 478842196, 6221523082, 87002638276, 1302313974900, 20763508263000, 351019617373500, 6266271456118776, 117671982989344680, 2316256222907194304, 47635421509263043024, 1020455890785584587168
Offset: 1

Views

Author

Jesse Carlsson (j.carlsson(AT)physics.unimelb.edu.au), Jun 25 2002

Keywords

Crossrefs

Cf. A052399 for T_6(n), A047890 for T_5(n), A047889 for T_4(n).
Column k=8 of A214015.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<4, n!,
          (-147456*(n+4)*(n-1)^2*(n-2)^2*(n-3)^2*a(n-4)
          +128*(33876+30709*n+6687*n^2+410*n^3)*(n-1)^2*(n-2)^2*a(n-3)
          -4*(1092*n^5+37140*n^4+455667*n^3+2387171*n^2+4649270*n+1206000)*
          (n-1)^2*a(n-2) +(-17075520+(22488312+(29223280+(10509820+(1764252+
          (154164+(6804+120*n)*n)*n)*n)*n)*n)*n)*a(n-1))/
          ((n+16)*(n+7)^2*(n+15)^2*(n+12)^2))
        end:
    seq(a(n), n=1..30);  # Alois P. Heinz, Sep 28 2012
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1&, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 8, n!, g[n, 8, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)

Formula

a(n) ~ 1913625 * 2^(6*n + 77) / (n^(63/2) * Pi^(7/2)). - Vaclav Kotesovec, Sep 10 2014

A072133 T_9(n) in the notation of Bergeron et al., u_k(n) in the notation of Gessel: Related to Young tableaux of bounded height.

Original entry on oeis.org

1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628799, 39916699, 478995537, 6226736369, 87166698628, 1307240982000, 20907446718225, 355162464899601, 6384776070987990, 121061600999380138, 2413632612087046844, 50453964720806671644, 1102844526263334763556
Offset: 0

Views

Author

Jesse Carlsson (j.carlsson(AT)physics.unimelb.edu.au), Jun 25 2002

Keywords

Crossrefs

Cf. A052399 for T_6(n), A047890 for T_5(n), A047889 for T_4(n).
Column k=9 of A214015.

Programs

  • Maple
    a:= proc(n) option remember;
          `if`(n<5, n!, ((-1110790863+(1520978576+(1772290401+(607308786+
           (101671498+(9464664+(500874+(14124+165*n)*n)*n)*n)*n)*n)*n)*n)*a(n-1)
           -(1129886062*n+559908333*n^2+111239576*n^3+10655238*n^4+8778*n^6
           +491700*n^5 +353895381)*(n-1)^2*a(n-2) +(258011271+234066216*n
           +58221266*n^2+5463876*n^3 +172810*n^4)*(n-1)^2*(n-2)^2*a(n-3)
           -9*(4070430+1504292*n+117469*n^2)* (n-1)^2*(n-2)^2*(n-3)^2*a(n-4)
           +893025*(n-1)^2*(n-2)^2*(n-3)^2*(n-4)^2*a(n-5)) /
           ((n+20)^2*(n+8)^2*(n+18)^2*(n+14)^2))
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Oct 10 2012
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1 &, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i - 1, Join[l, Array[i &, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 9, n!, g[n, 9, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)

Formula

a(n) ~ 30625 * 3^(4*n + 90) / (2097152 * n^40 * Pi^4). - Vaclav Kotesovec, Sep 10 2014

Extensions

a(0)=1 prepended by Alois P. Heinz, Feb 09 2017
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