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 11 results. Next

A244657 Number T(n,k) of n-node unlabeled rooted trees with thinning limbs and root outdegree (branching factor) 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, 1, 1, 1, 0, 1, 3, 1, 1, 0, 1, 4, 3, 1, 1, 0, 1, 9, 6, 3, 1, 1, 0, 1, 13, 13, 6, 3, 1, 1, 0, 1, 26, 25, 15, 6, 3, 1, 1, 0, 1, 42, 55, 29, 15, 6, 3, 1, 1, 0, 1, 81, 107, 68, 31, 15, 6, 3, 1, 1, 0, 1, 138, 224, 140, 72, 31, 15, 6, 3, 1, 1
Offset: 1

Views

Author

Alois P. Heinz, Jul 04 2014

Keywords

Comments

In a rooted tree with thinning limbs the outdegree of a parent node is larger than or equal to the outdegree of any of its child nodes.

Examples

			The A124343(5) = 6 5-node rooted trees with thinning limbs sorted by root outdegree 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  :                     :       :         :
:     :                     :       :         :
: -1- : ---------2--------- : --3-- : ---4--- :
Thus row 5 = [0, 1, 3, 1, 1].
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,  1;
  0, 1,  1,   1;
  0, 1,  3,   1,  1;
  0, 1,  4,   3,  1,  1;
  0, 1,  9,   6,  3,  1,  1;
  0, 1, 13,  13,  6,  3,  1, 1;
  0, 1, 26,  25, 15,  6,  3, 1, 1;
  0, 1, 42,  55, 29, 15,  6, 3, 1, 1;
  0, 1, 81, 107, 68, 31, 15, 6, 3, 1, 1;
		

Crossrefs

Columns k=0-10 give: A000007(n-1), A000012 (for n>1), A244703, A244704, A244705, A244706, A244707, A244708, A244709, A244710, A244711.
T(2n,n) gives A244712.
Row sums give A124343.

Programs

  • Maple
    b:= proc(n, i, h, v) option remember; `if`(n=0,
          `if`(v=0, 1, 0), `if`(i<1 or v<1 or n b(n-1$2, k$2):
    seq(seq(T(n, k), k=0..n-1), n=1..14);
  • Mathematica
    b[n_, i_, h_, v_] := b[n, i, h, v] = If[n == 0, If[v == 0, 1, 0], If[i<1 || v<1 || nJean-François Alcover, Feb 03 2015, after Alois P. Heinz *)

A245142 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 2.

Original entry on oeis.org

1, 0, 1, 1, 3, 3, 8, 9, 21, 28, 56, 81, 159, 237, 444, 701, 1273, 2060, 3699, 6099, 10840, 18180, 32079, 54417, 95787, 163868, 287914, 496171, 871270, 1509676, 2652068, 4615810, 8114578, 14176261, 24947471, 43718822, 77031659, 135350915, 238791685, 420544851
Offset: 3

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=2 of A245151.

A245143 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 3.

Original entry on oeis.org

1, 0, 0, 1, 1, 1, 3, 3, 5, 9, 12, 17, 32, 42, 64, 106, 157, 232, 379, 563, 866, 1362, 2081, 3186, 5028, 7710, 11924, 18659, 28938, 44842, 70254, 109245, 170266, 266562, 416378, 650513, 1020431, 1597803, 2504070, 3932672, 6174777, 9698203, 15258753, 24005178
Offset: 4

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=3 of A245151.

A245144 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 4.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 1, 1, 3, 3, 5, 5, 11, 12, 19, 24, 41, 51, 78, 101, 163, 215, 320, 431, 661, 908, 1333, 1846, 2745, 3847, 5630, 7913, 11620, 16481, 23991, 34134, 49782, 71196, 103416, 148178, 215511, 309881, 449941, 647868, 941279, 1358857, 1973315, 2851880
Offset: 5

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=4 of A245151.

A245145 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 5.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 11, 14, 19, 26, 32, 49, 63, 87, 114, 157, 215, 292, 396, 536, 719, 1002, 1345, 1849, 2496, 3395, 4644, 6344, 8647, 11800, 16049, 21990, 29980, 41087, 56048, 76642, 104863, 143498, 196454, 269057, 368191, 504806
Offset: 6

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=5 of A245151.

A245146 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 6.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 7, 13, 14, 21, 26, 34, 40, 61, 72, 100, 127, 171, 209, 295, 367, 499, 638, 851, 1083, 1469, 1879, 2512, 3257, 4320, 5576, 7454, 9662, 12833, 16752, 22163, 28874, 38308, 50056, 66232, 86865, 114784, 150429
Offset: 7

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=6 of A245151.

A245147 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 7.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 7, 9, 13, 16, 21, 28, 34, 42, 52, 70, 85, 113, 141, 185, 227, 290, 371, 474, 602, 771, 983, 1254, 1583, 2038, 2582, 3315, 4217, 5405, 6867, 8783, 11201, 14318, 18285, 23395, 29886, 38207, 48765, 62428
Offset: 8

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=7 of A245151.

A245148 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 8.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 15, 16, 23, 28, 36, 42, 54, 61, 83, 98, 127, 155, 203, 242, 309, 370, 479, 578, 739, 904, 1155, 1420, 1790, 2194, 2786, 3425, 4323, 5350, 6747, 8362, 10522, 13022, 16397, 20346, 25558
Offset: 9

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=8 of A245151.

A245149 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 9.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 11, 15, 18, 23, 30, 36, 44, 54, 63, 74, 96, 112, 141, 173, 218, 261, 328, 390, 479, 587, 716, 873, 1080, 1322, 1628, 1998, 2446, 2982, 3677, 4481, 5507, 6744, 8296, 10155, 12521
Offset: 10

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=9 of A245151.

A245150 Number of n-node unlabeled rooted trees with thickening limbs and root outdegree (branching factor) 10.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 11, 11, 17, 18, 25, 30, 38, 44, 56, 63, 76, 87, 110, 126, 159, 188, 237, 280, 348, 410, 503, 588, 726, 854, 1050, 1248, 1534, 1837, 2251, 2694, 3282, 3921, 4784, 5717, 6955
Offset: 11

Views

Author

Alois P. Heinz, Jul 12 2014

Keywords

Crossrefs

Column k=10 of A245151.
Showing 1-10 of 11 results. Next