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 10 results.

A244454 Number T(n,k) of unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals k; triangle T(n,k), n>=1, 0<=k<=n-1, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 3, 0, 1, 0, 7, 1, 0, 1, 0, 17, 2, 0, 0, 1, 0, 42, 4, 1, 0, 0, 1, 0, 105, 7, 2, 0, 0, 0, 1, 0, 267, 15, 2, 1, 0, 0, 0, 1, 0, 684, 28, 4, 2, 0, 0, 0, 0, 1, 0, 1775, 56, 7, 2, 1, 0, 0, 0, 0, 1, 0, 4639, 110, 12, 2, 2, 0, 0, 0, 0, 0, 1
Offset: 1

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 28 2014

Keywords

Comments

T(1,0) = 1 by convention.
Sum_{i=2..n-1} T(n,i) = A001678(n+1) for n>1.

Examples

			The A000081(5) = 9 rooted trees with 5 nodes sorted by minimal outdegree of inner nodes are:
: o   o     o     o     o     o     o   :     o   :    o    :
: |   |     |    / \   / \    |    /|\  :    / \  :  /( )\  :
: o   o     o   o   o o   o   o   o o o :   o   o : o o o o :
: |   |    / \  |     |   |  /|\  |     :  / \    :         :
: o   o   o   o o     o   o o o o o     : o   o   :         :
: |  / \  |     |                       :         :         :
: o o   o o     o                       :         :         :
: |                                     :         :         :
: o                                     :         :         :
:                                       :         :         :
: ------------------1------------------ : ---2--- : ---4--- :
Thus row 5 = [0, 7, 1, 0, 1].
Triangle T(n,k) begins:
  1;
  0,    1;
  0,    1,   1;
  0,    3,   0,  1;
  0,    7,   1,  0, 1;
  0,   17,   2,  0, 0, 1;
  0,   42,   4,  1, 0, 0, 1;
  0,  105,   7,  2, 0, 0, 0, 1;
  0,  267,  15,  2, 1, 0, 0, 0, 1;
  0,  684,  28,  4, 2, 0, 0, 0, 0, 1;
  0, 1775,  56,  7, 2, 1, 0, 0, 0, 0, 1;
  0, 4639, 110, 12, 2, 2, 0, 0, 0, 0, 0, 1;
		

Crossrefs

Row sums give A000081.
Cf. A001678, A244372, A244530 (ordered unlabeled rooted trees).

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, `if`(t in [0, k],
          1, 0), `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
          b(n-i*j, i-1, max(0, t-j), k), j=0..n/i)))
        end:
    T:= (n, k)-> b(n-1$2, k$2) -`if`(n=1 and k=0, 0, b(n-1$2, k+1$2)):
    seq(seq(T(n, k), k=0..n-1), n=1..14);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, If[t == 0 || t == k, 1, 0], If[i<1, 0, Sum[Binomial[b[i-1, i-1, k, k]+j-1, j]* b[n-i*j, i-1, Max[0, t-j], k], {j, 0, n/i}]]]; T[n_, k_] := b[n-1, n-1, k, k] - If[n == 1 && k == 0, 0, b[n-1, n-1, k+1, k+1]]; Table[Table[T[n, k], {k, 0, n-1}], {n, 1, 14}] // Flatten (* Jean-François Alcover, Jan 08 2015, translated from Maple *)

A244531 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 2.

Original entry on oeis.org

1, 0, 2, 5, 11, 28, 78, 201, 532, 1441, 3895, 10569, 28926, 79493, 219226, 607189, 1687880, 4706737, 13165215, 36929595, 103860429, 292808814, 827392709, 2342964435, 6647953886, 18898472568, 53818654942, 153518738980, 438602656951, 1254943919799, 3595714927194
Offset: 3

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=2 of A244530.
Cf. A244456.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 2$2) -b(n-1, 3$2):
    seq(a(n), n=3..50);
  • Mathematica
    b[n_, t_, k_] := b[n, t, k] = If[n == 0, If[t == 0 || t == k, 1, 0], If[t > n, 0, Sum[b[j - 1, k, k]*b[n - j, Max[0, t - 1], k], {j, 1, n}]]]; T[n_, k_] := b[n - 1, k, k] - If[n == 1 && k == 0, 0, b[n - 1, k + 1, k + 1]]; a[n_] := b[n - 1, 2, 2] - b[n - 1, 3, 3]; Table[a[n], {n, 3, 50}] (* Jean-François Alcover, Feb 06 2015, after Maple *)

Formula

Recurrence: (n-2)*n*(n+1)*(31556*n^6 - 602602*n^5 + 4562565*n^4 - 17272550*n^3 + 33523297*n^2 - 29665770*n + 7578864)*a(n) = -2*(n-4)*n*(15778*n^6 - 93541*n^5 - 718683*n^4 + 7746097*n^3 - 25426183*n^2 + 35870760*n - 18623988)*a(n-1) + 2*(189336*n^9 - 4357178*n^8 + 42198478*n^7 - 222932639*n^6 + 692179375*n^5 - 1246825745*n^4 + 1121148607*n^3 - 95771898*n^2 - 622360656*n + 342066240)*a(n-2) + 4*(15778*n^9 - 301301*n^8 + 2556736*n^7 - 13524389*n^6 + 51959635*n^5 - 145042550*n^4 + 255185823*n^3 - 199177680*n^2 - 62590212*n + 146335680)*a(n-3) - 2*(n-4)*(63112*n^8 - 1252538*n^7 + 9554713*n^6 - 31464554*n^5 + 11620330*n^4 + 221568106*n^3 - 627283143*n^2 + 624591414*n - 146644560)*a(n-4) - 4*(n-5)*(n-4)*(504896*n^7 - 9428629*n^6 + 69275668*n^5 - 250040744*n^4 + 437755491*n^3 - 253595994*n^2 - 179277570*n + 187109352)*a(n-5) - 69*(n-6)*(n-5)*(n-4)*(31556*n^6 - 413266*n^5 + 2022895*n^4 - 4417190*n^3 + 3528357*n^2 + 989760*n - 1844640)*a(n-6). - Vaclav Kotesovec, Jul 02 2014
a(n) ~ 3^(n+1/2) / (8*sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Jul 02 2014

A244532 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 3.

Original entry on oeis.org

1, 0, 0, 3, 7, 8, 21, 55, 121, 265, 611, 1379, 3193, 7436, 17085, 39339, 91846, 214549, 500132, 1169267, 2743302, 6445797, 15167805, 35749961, 84390645, 199523566, 472429633, 1120012481, 2658525869, 6318368820, 15034189965, 35811690663, 85393261630
Offset: 4

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=3 of A244530.
Cf. A244457.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 3$2) -b(n-1, 4$2):
    seq(a(n), n=4..40);
  • Mathematica
    b[n_, t_, k_] := b[n, t, k] = If[n == 0, If[t == 0 || t == k, 1, 0], If[t > n, 0, Sum[b[j - 1, k, k]*b[n - j, Max[0, t - 1], k], {j, 1, n}]]]; T[n_, k_] := b[n - 1, k, k] - If[n == 1 && k == 0, 0, b[n - 1, k + 1, k + 1]]; a[n_] := b[n - 1, 3, 3] - b[n - 1, 4, 4]; Table[a[n], {n, 4, 40}] (* Jean-François Alcover, Feb 06 2015, after Maple *)

Formula

a(n) ~ sqrt(sqrt(2)/4 - sqrt(154+112*sqrt(2))/56) * ((sqrt(13+16*sqrt(2))-1)/2)^n / (sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Jul 02 2014

A244533 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 4.

Original entry on oeis.org

1, 0, 0, 0, 4, 9, 10, 11, 34, 91, 196, 330, 636, 1377, 2976, 6061, 12199, 25186, 52767, 109066, 224964, 467605, 979056, 2042847, 4244986, 8844130, 18527956, 38878929, 81460220, 170576593, 357894472, 752544917, 1583579674, 3332453026, 7016669752, 14790212086
Offset: 5

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=4 of A244530.
Cf. A244458.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 4$2) -b(n-1, 5$2):
    seq(a(n), n=5..45);
  • Mathematica
    b[n_, t_, k_] := b[n, t, k] = If[n == 0, If[t == 0 || t == k, 1, 0], If[t > n, 0, Sum[b[j - 1, k, k]*b[n - j, Max[0, t - 1], k], {j, 1, n}]]]; T[n_, k_] := b[n - 1, k, k] - If[n == 1 && k == 0, 0, b[n - 1, k + 1, k + 1]]; a[n_] := b[n - 1, 4, 4] - b[n - 1, 5, 5]; Table[a[n], {n, 5, 45}] (* Jean-François Alcover, Feb 06 2015, after Maple *)

Formula

a(n) ~ c * d^n / (sqrt(Pi) * n^(3/2)), where d = 2.18452974131524781307797151868229485574758... is the root of the equation -229 - 36*d + 2*d^2 - 32*d^3 + 19*d^4 + 4*d^5 = 0, and c = 0.181069926661856899940163775713243367029404419526724... . - Vaclav Kotesovec, Jul 02 2014

A244534 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 5.

Original entry on oeis.org

1, 0, 0, 0, 0, 5, 11, 12, 13, 14, 50, 136, 289, 477, 703, 1255, 2611, 5489, 10902, 19712, 35455, 66651, 130014, 254737, 488041, 920461, 1741642, 3338360, 6453073, 12425997, 23780944, 45451155, 87224392, 168253246, 324863578, 625728091, 1202953325, 2314485753
Offset: 6

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=5 of A244530.
Cf. A244459.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 5$2) -b(n-1, 6$2):
    seq(a(n), n=6..50);
  • Mathematica
    b[n_, t_, k_] := b[n, t, k] = If[n == 0,
         If[MemberQ[{0, k}, t], 1, 0], If[t > n, 0, Sum[b[j-1, k, k]*
         b[n-j, Max[0, t-1], k], {j, n}]]];
    a[n_] := b[n-1, 5, 5] - b[n-1, 6, 6];
    Table[a[n], {n, 6, 50}] (* Jean-François Alcover, Aug 28 2021, after Maple code *)

A244535 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 6.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 6, 13, 14, 15, 16, 17, 69, 190, 400, 651, 946, 1288, 2186, 4425, 9126, 17811, 31654, 51997, 85841, 149916, 276056, 518089, 960466, 1718395, 3006963, 5269873, 9392821, 17032418, 31098198, 56432687, 101350402, 180978701, 323731177, 582832779
Offset: 7

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=6 of A244530.
Cf. A244460.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 6$2) -b(n-1, 7$2):
    seq(a(n), n=7..50);

A244536 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 7.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 7, 15, 16, 17, 18, 19, 20, 91, 253, 529, 852, 1225, 1651, 2133, 3493, 6931, 14095, 27156, 47648, 77297, 118031, 182462, 300441, 527398, 954712, 1722370, 3015910, 5074611, 8342271, 13730760, 23036563, 39558564, 68974240, 120541276
Offset: 8

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=7 of A244530.
Cf. A244461.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 7$2) -b(n-1, 8$2):
    seq(a(n), n=8..50);

A244537 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 8.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 8, 17, 18, 19, 20, 21, 22, 23, 116, 325, 676, 1080, 1540, 2059, 2640, 3286, 5240, 10241, 20604, 39305, 68286, 109705, 165946, 239629, 351898, 552311, 931070, 1633871, 2879668, 4951860, 8208631, 13094200, 20436400, 31939817, 50935060
Offset: 9

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=8 of A244530.
Cf. A244462.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 8$2) -b(n-1, 9$2):
    seq(a(n), n=9..55);

A244538 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 9.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 9, 19, 20, 21, 22, 23, 24, 25, 26, 144, 406, 841, 1335, 1891, 2512, 3201, 3961, 4795, 7491, 14467, 28861, 54626, 94160, 150101, 225337, 323016, 446556, 629454, 949486, 1545877, 2639756, 4558225, 7716325, 12629776, 19928727, 30372551
Offset: 10

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=9 of A244530.
Cf. A244463.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 9$2) -b(n-1, 10$2):
    seq(a(n), n=10..60);

A244539 Number of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals 10.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 21, 22, 23, 24, 25, 26, 27, 28, 29, 175, 496, 1024, 1617, 2278, 3010, 3816, 4699, 5662, 6708, 10310, 19721, 39074, 73487, 125862, 199365, 297436, 423799, 582472, 777777, 1060410, 1547051, 2443649, 4072732, 6905106, 11528110
Offset: 11

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 29 2014

Keywords

Crossrefs

Column k=10 of A244530.
Cf. A244464.

Programs

  • Maple
    b:= proc(n, t, k) option remember; `if`(n=0,
          `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*
           b(n-j, max(0, t-1), k), j=1..n)))
        end:
    a:= n-> b(n-1, 10$2) -b(n-1, 11$2):
    seq(a(n), n=11..60);
Showing 1-10 of 10 results.