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 1-5 of 5 results.

A258829 Number T(n,k) of permutations p of [n] such that the up-down signature of 0,p has nonnegative partial sums with a maximal value of k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 5, 11, 3, 1, 0, 16, 38, 28, 4, 1, 0, 61, 263, 130, 62, 5, 1, 0, 272, 1260, 1263, 340, 129, 6, 1, 0, 1385, 10871, 8090, 4734, 819, 261, 7, 1, 0, 7936, 66576, 88101, 33855, 16066, 1890, 522, 8, 1, 0, 50521, 694599, 724189, 495371, 127538, 52022, 4260, 1040, 9, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 11 2015

Keywords

Examples

			p = 1432 is counted by T(4,2) because the up-down signature of 0,p = 01432 is 1,1,-1,-1 with partial sums 1,2,1,0.
q = 4321 is not counted by any T(4,k) because the up-down signature of 0,q = 04321 is 1,-1,-1,-1 with partial sums 1,0,-1,-2.
T(4,1) = 5: 2143, 3142, 3241, 4132, 4231.
T(4,2) = 11: 1324, 1423, 1432, 2134, 2314, 2413, 2431, 3124, 3412, 3421, 4123.
T(4,3) = 3: 1243, 1342, 2341.
T(4,4) = 1: 1234.
Triangle T(n,k) begins:
  1;
  0,    1;
  0,    1,     1;
  0,    2,     2,    1;
  0,    5,    11,    3,    1;
  0,   16,    38,   28,    4,   1;
  0,   61,   263,  130,   62,   5,   1;
  0,  272,  1260, 1263,  340, 129,   6, 1;
  0, 1385, 10871, 8090, 4734, 819, 261, 7, 1;
		

Crossrefs

Row sums give A258830.
T(2n,n) gives A266947.

Programs

  • Maple
    b:= proc(u, o, c, k) option remember;
          `if`(c<0 or c>k, 0, `if`(u+o=0, 1,
           add(b(u-j, o-1+j, c+1, k), j=1..u)+
           add(b(u+j-1, o-j, c-1, k), j=1..o)))
        end:
    A:= (n, k)-> b(n, 0$2, k):
    T:= (n, k)-> A(n, k) -`if`(k=0, 0, A(n, k-1)):
    seq(seq(T(n, k), k=0..n), n=0..12);
  • Mathematica
    b[u_, o_, c_, k_] := b[u, o, c, k] = If[c < 0 || c > k, 0, If[u + o == 0, 1, Sum[b[u - j, o - 1 + j, c + 1, k], {j, 1, u}] + Sum[b[u + j - 1, o - j, c - 1, k], {j, 1, o}]]];
    A[n_, k_] := b[n, 0, 0, k];
    T[n_, k_] :=  A[n, k] - If[k == 0, 0, A[n, k - 1]];
    Table[T[n, k], {n, 0, 12}, { k, 0, n}] // Flatten (* Jean-François Alcover, Jun 09 2018, after Alois P. Heinz *)

Formula

T(n,k) = A262163(n,k) - A262163(n,k-1) for k>0, T(n,0) = A262163(n,0).

A291722 Number T(n,k) of permutations p of [n] such that in 0p the sum of all jumps equals k + n; triangle T(n,k), n >= 0, 0 <= k <= n*(n-1)/2, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 1, 6, 6, 5, 4, 1, 1, 1, 10, 20, 20, 26, 15, 15, 6, 5, 1, 1, 1, 15, 50, 70, 105, 106, 104, 90, 65, 51, 27, 21, 7, 6, 1, 1, 1, 21, 105, 210, 350, 497, 554, 644, 567, 574, 420, 386, 238, 203, 105, 85, 35, 28, 8, 7, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Aug 30 2017

Keywords

Comments

An up-jump j occurs at position i in p if p_{i} > p_{i-1} and j is the index of p_i in the increasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are larger than p_{i-1}. A down-jump j occurs at position i in p if p_{i} < p_{i-1} and j is the index of p_i in the decreasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are smaller than p_{i-1}. First index in the lists is 1 here.
From David B. Wilson, Dec 14 2018: (Start)
T(n,k) equals the number of permutations p of [n] such that twice the sum of the leftward-down-jumps of p plus the number of descents of p equals k.
T(n,k) equals the number of cover-inclusive Dyck tilings whose lower boundary is the zig-zag path of order n (UD)^n, and which have k tiles.
A leftward-down-jump j occurs at position i in p if p_{i} > p_{i+1} and there are j positions k for which k p_k > p_{i+1}.
Cover-inclusive Dyck tilings are defined in the Kenyon and Wilson link below. (End)

Examples

			T(4,0) = 1: 1234.
T(4,1) = 6: 1243, 1324, 1342, 2134, 2314, 2341.
T(4,2) = 6: 1432, 2143, 2431, 3214, 3241, 3421.
T(4,3) = 5: 1423, 2413, 3124, 3412, 4321.
T(4,4) = 4: 3142, 4213, 4231, 4312.
T(4,5) = 1: 4123.
T(4,6) = 1: 4132.
T(5,5) = 15: 15234, 25134, 31542, 35124, 41235, 42153, 42531, 43152, 45123, 53214, 53241, 53421, 54213, 54231, 54312.
Triangle T(n,k) begins:
  1;
  1;
  1,  1;
  1,  3,  1,  1;
  1,  6,  6,  5,   4,   1,   1;
  1, 10, 20, 20,  26,  15,  15,  6,  5,  1,  1;
  1, 15, 50, 70, 105, 106, 104, 90, 65, 51, 27, 21, 7, 6, 1, 1;
		

Crossrefs

Columns k=0-3 give: A000012, A000217(n-1) for n>0, A002415(n-1) for n>0, A291288(n-3) for n>0.
Row sums give A000142.
T(n,n) gives A289489.

Programs

  • Maple
    b:= proc(u, o) option remember; expand(`if`(u+o=0, 1,
          add(b(u-j, o+j-1)*x^(j-1), j=1..u)+
          add(b(u+j-1, o-j)*x^(j-1), j=1..o)))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(0, n)):
    seq(T(n), n=0..10);
  • Mathematica
    (* Generating function for tiles for Dyck tilings above the zigzag path of order n *)
    (* Computed by looking at descents in the insertion sequence for the Dyck-tiling-ribbon bijection, described in the Kim-Meszaros-Panova-Wilson reference *)
    (* Since it's above the zigzag, all insertion positions are even *)
    (* When the second argument is specified, refines by position of last insertion *)
    tilegen[n_, sn_] := tilegen[n, sn] = If[n == 0 || n == 1, 1,
        Sum[tilegen[n - 1, j] If[j >= sn, t^(j - sn + 1), 1] //
          Expand, {j, 0, 2 (n - 2), 2}]
        ];
    tilegen[n_] := tilegen[n + 1, 2 n];
    T[n_, k_] := Coefficient[tilegen[n], t, k]; (* David B. Wilson, Dec 14 2018 *)

Formula

Sum_{k>=0} k * T(n,k) = A005990(n).

A303697 Number T(n,k) of permutations p of [n] whose difference between sum of up-jumps and sum of down-jumps equals k; triangle T(n,k), n>=0, min(0,1-n)<=k<=max(0,n-1), read by rows.

Original entry on oeis.org

1, 1, 1, 0, 1, 1, 1, 2, 1, 1, 1, 4, 5, 4, 5, 4, 1, 1, 11, 19, 19, 20, 19, 19, 11, 1, 1, 26, 82, 100, 101, 100, 101, 100, 82, 26, 1, 1, 57, 334, 580, 619, 619, 620, 619, 619, 580, 334, 57, 1, 1, 120, 1255, 3394, 4339, 4420, 4421, 4420, 4421, 4420, 4339, 3394, 1255, 120, 1
Offset: 0

Author

Alois P. Heinz, Apr 28 2018

Keywords

Comments

An up-jump j occurs at position i in p if p_{i} > p_{i-1} and j is the index of p_i in the increasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are larger than p_{i-1}. A down-jump j occurs at position i in p if p_{i} < p_{i-1} and j is the index of p_i in the decreasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are smaller than p_{i-1}. First index in the lists is 1 here.

Examples

			Triangle T(n,k) begins:
:                               1                             ;
:                               1                             ;
:                          1,   0,   1                        ;
:                     1,   1,   2,   1,   1                   ;
:                1,   4,   5,   4,   5,   4,   1              ;
:           1,  11,  19,  19,  20,  19,  19,  11,   1         ;
:      1,  26,  82, 100, 101, 100, 101, 100,  82,  26,  1     ;
:  1, 57, 334, 580, 619, 619, 620, 619, 619, 580, 334, 57, 1  ;
		

Programs

  • Maple
    b:= proc(u, o) option remember; expand(`if`(u+o=0, 1,
          add(b(u-j, o+j-1)*x^(-j), j=1..u)+
          add(b(u+j-1, o-j)*x^( j), j=1..o)))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=ldegree(p)..degree(p)))(
            `if`(n=0, 1, add(b(j-1, n-j), j=1..n))):
    seq(T(n), n=0..12);
  • Mathematica
    b[u_, o_] := b[u, o] = Expand[If[u+o == 0, 1,
         Sum[b[u-j, o+j-1] x^-j, {j, 1, u}] +
         Sum[b[u+j-1, o-j] x^j, {j, 1, o}]]];
    T[0] = {1};
    T[n_] := x^n Sum[b[j-1, n-j], {j, 1, n}] // CoefficientList[#, x]& // Rest;
    T /@ Range[0, 12] // Flatten (* Jean-François Alcover, Feb 20 2021, after Alois P. Heinz *)

Formula

T(n,0) = A153229(n) for n > 0.
T(n,1) = A005165(n-1) for n > 0.
T(n+1,n-1) = A000295(n).
T(n,k) = T(n,-k).
Sum_{k=0..n-1} k^2 * T(n,k) = A001720(n+2) for n>1.

A316292 Number T(n,k) of permutations p of [n] such that k is the maximum of the partial sums of the signed up-down jump sequence of 0,p; triangle T(n,k), n>=0, ceiling((sqrt(1+8*n)-1)/2)<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 2, 1, 5, 8, 16, 5, 50, 65, 1, 79, 314, 326, 69, 872, 2142, 1957, 34, 1539, 8799, 16248, 13700, 9, 1823, 24818, 89273, 137356, 109601, 1, 1494, 50561, 355271, 947713, 1287350, 986410, 856, 76944, 1070455, 4923428, 10699558, 13281458, 9864101
Offset: 0

Author

Alois P. Heinz, Jun 28 2018

Keywords

Comments

An up-jump j occurs at position i in p if p_{i} > p_{i-1} and j is the index of p_i in the increasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are larger than p_{i-1}. A down-jump -j occurs at position i in p if p_{i} < p_{i-1} and j is the index of p_i in the decreasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are smaller than p_{i-1}. First index in the lists is 1 here.

Examples

			Triangle T(n,k) begins:
: 1;
:    1;
:       2;
:       1, 5;
:          8, 16;
:          5, 50,   65;
:          1, 79,  314,   326;
:             69,  872,  2142,   1957;
:             34, 1539,  8799,  16248,  13700;
:              9, 1823, 24818,  89273, 137356,  109601;
:              1, 1494, 50561, 355271, 947713, 1287350, 986410;
		

Crossrefs

Row sums give A000142.
Column sums give A316294.
Main diagonal gives A000522.
Cf. A002024, A123578, A258829, A291722, A303697, A316293 (same read by columns).

Programs

  • Maple
    b:= proc(u, o, c, k) option remember;
          `if`(c>k, 0, `if`(u+o=0, 1,
           add(b(u-j, o-1+j, c+j, k), j=1..u)+
           add(b(u+j-1, o-j, c-j, k), j=1..o)))
        end:
    T:= (n, k)-> b(n, 0$2, k) -`if`(k=0, 0, b(n, 0$2, k-1)):
    seq(seq(T(n, k), k=ceil((sqrt(1+8*n)-1)/2)..n), n=0..14);
  • Mathematica
    b[u_, o_, c_, k_] := b[u, o, c, k] =
         If[c > k, 0, If[u + o == 0, 1,
         Sum[b[u - j, o - 1 + j, c + j, k], {j, 1, u}] +
         Sum[b[u + j - 1, o - j, c - j, k], {j, 1, o}]]];
    T[n_, k_] := b[n, 0, 0, k] - If[k == 0, 0, b[n, 0, 0, k - 1]];
    Table[Table[T[n, k], {k, Ceiling[(Sqrt[8n+1]-1)/2], n}], {n, 0, 14}] // Flatten (* Jean-François Alcover, Feb 27 2021, after Alois P. Heinz *)

A316294 Total number of permutations p of [k] such that n is the maximum of the partial sums of the signed up-down jump sequence of 0,p summed over all k >= 0.

Original entry on oeis.org

1, 1, 3, 19, 258, 7406, 442668, 54371100, 13585980916, 6859762797636, 6969135518632452, 14209819222900305044, 58061006907633910998660, 474996314819118381967232244, 7776635831062534849079443379908, 254723669580125156112963535996038036
Offset: 0

Author

Alois P. Heinz, Jun 28 2018

Keywords

Comments

An up-jump j occurs at position i in p if p_{i} > p_{i-1} and j is the index of p_i in the increasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are larger than p_{i-1}. A down-jump -j occurs at position i in p if p_{i} < p_{i-1} and j is the index of p_i in the decreasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are smaller than p_{i-1}. First index in the lists is 1 here.

Crossrefs

Column sums of A316292 or A316293.

Programs

  • Maple
    b:= proc(u, o, c, k) option remember;
          `if`(c>k, 0, `if`(u+o=0, 1,
           add(b(u-j, o-1+j, c+j, k), j=1..u)+
           add(b(u+j-1, o-j, c-j, k), j=1..o)))
        end:
    a:= n-> add(b(k, 0$2, n)-b(k, 0$2, n-1), k=n..n*(n+1)/2):
    seq(a(n), n=0..15);
  • Mathematica
    b[u_, o_, c_, k_] := b[u, o, c, k] =
         If[c > k, 0, If[u + o == 0, 1,
         Sum[b[u - j, o - 1 + j, c + j, k], {j, u}] +
         Sum[b[u + j - 1, o - j, c - j, k], {j, o}]]];
    a[n_] := Sum[b[k, 0, 0, n] - b[k, 0, 0, n-1], {k, n, n(n+1)/2}];
    Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Sep 01 2021, after Alois P. Heinz *)
Showing 1-5 of 5 results.