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.

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A292555 Number of rooted unlabeled trees on n nodes where each node has at most 10 children.

Original entry on oeis.org

1, 1, 1, 2, 4, 9, 20, 48, 115, 286, 719, 1842, 4765, 12483, 32964, 87785, 235305, 634628, 1720524, 4686842, 12820920, 35206475, 97010705, 268154003, 743351390, 2066090876, 5756490561, 16074597300, 44980514021, 126109353817, 354202275766, 996517941454
Offset: 0

Views

Author

Marko Riedel, Sep 18 2017

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> `if`(n=0, 1, b(n-1$2, 10$2)):
    seq(a(n), n=0..35);  # Alois P. Heinz, Sep 20 2017
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[ Binomial[b[i - 1, i - 1, k, k] + j - 1, j]*b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]]];
    a[n_] := If[n == 0, 1, b[n - 1, n - 1, 10, 10]];
    Table[a[n], {n, 0, 35}] (* Jean-François Alcover, Jun 04 2018, after Alois P. Heinz *)

Formula

Functional equation of G.f. is T(z) = z + z*Sum_{q=1..10} Z(S_q)(T(z)) with Z(S_q) the cycle index of the symmetric group. Alternate FEQ is
T(z) = 1 + z*Z(S_10)(T(z)).
a(n) = Sum_{j=1..10} A244372(n,j) for n>0, a(0) = 1. - Alois P. Heinz, Sep 20 2017
a(n) / a(n+1) ~ 0.338329194566131211670667671160855741193081902868090986608524... - Robert A. Russell, Feb 11 2023

A182378 G.f. satisfies A(x) = 1 + x*cycle_index(Sym(7), A(x)).

Original entry on oeis.org

1, 1, 1, 2, 4, 9, 20, 48, 115, 285, 716, 1833, 4740, 12410, 32754, 87176, 233547, 629540, 1705809, 4644231, 12697500, 34848694, 95973026, 265142431, 734606478, 2040683413, 5682634446, 15859800889, 44355531103, 124290064228, 348904212741, 981082979409
Offset: 0

Views

Author

Michael Burkhart, Apr 26 2012

Keywords

Comments

Number of rooted trees where each node has at most 7 children.

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> `if`(n=0, 1, b(n-1$2, 7$2)):
    seq(a(n), n=0..35);  # Alois P. Heinz, Sep 20 2017
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[ Binomial[ b[i-1, i-1, k, k] + j - 1, j]*b[n-i*j, i-1, t-j, k], {j, 0, Min[t, n/i]}]]];
    a[n_] := If[n == 0, 1, b[n-1, n-1, 7, 7]];
    Table[a[n], {n, 0, 35}] (* Jean-François Alcover, Jan 15 2018, after Alois P. Heinz *)

Formula

a(n) = Sum_{j=1..7} A244372(n,j) for n>0, a(0) = 1. - Alois P. Heinz, Sep 19 2017
a(n) / a(n+1) ~ 0.338512011286603947719604869750539045616436718225097926729820... - Robert A. Russell, Feb 11 2023

Extensions

More terms from Patrick Devlin, Apr 29 2012

A244523 Irregular triangle read by rows: T(n,k) is the number of identity trees with n nodes and maximal branching factor k.

Original entry on oeis.org

1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 2, 0, 1, 5, 0, 1, 10, 1, 0, 1, 21, 3, 0, 1, 42, 9, 0, 1, 87, 25, 0, 1, 178, 66, 2, 0, 1, 371, 170, 6, 0, 1, 773, 431, 21, 0, 1, 1630, 1076, 63, 0, 1, 3447, 2665, 185, 1, 0, 1, 7346, 6560, 512, 7, 0, 1, 15712, 16067, 1403, 26, 0, 1, 33790, 39219, 3750, 91, 0, 1, 72922, 95476, 9928, 291
Offset: 1

Views

Author

Joerg Arndt and Alois P. Heinz, Jul 30 2014

Keywords

Comments

Row sums give A004111.

Examples

			Triangle starts:
01:  1,
02:  0, 1,
03:  0, 1,
04:  0, 1, 1,
05:  0, 1, 2,
06:  0, 1, 5,
07:  0, 1, 10, 1,
08:  0, 1, 21, 3,
09:  0, 1, 42, 9,
10:  0, 1, 87, 25,
11:  0, 1, 178, 66, 2,
12:  0, 1, 371, 170, 6,
13:  0, 1, 773, 431, 21,
14:  0, 1, 1630, 1076, 63,
15:  0, 1, 3447, 2665, 185, 1,
16:  0, 1, 7346, 6560, 512, 7,
17:  0, 1, 15712, 16067, 1403, 26,
18:  0, 1, 33790, 39219, 3750, 91,
19:  0, 1, 72922, 95476, 9928, 291,
20:  0, 1, 158020, 231970, 25969, 885, 3,
21:  0, 1, 343494, 562736, 67462, 2588, 15,
22:  0, 1, 749101, 1363640, 174039, 7373, 70,
23:  0, 1, 1638102, 3301586, 446884, 20555, 256,
24:  0, 1, 3591723, 7988916, 1142457, 56413, 884,
25:  0, 1, 7893801, 19322585, 2911078, 152812, 2840, 3,
...
The A004111(7) = 12 level-sequences and the branching sequences for the identity trees with 7 nodes are (dots for zeros), together with the maximal branching factors, are:
01:  [ . 1 2 3 4 5 6 ]    [ 1 1 1 1 1 1 . ]   1
02:  [ . 1 2 3 4 5 4 ]    [ 1 1 1 2 1 . . ]   2
03:  [ . 1 2 3 4 5 3 ]    [ 1 1 2 1 1 . . ]   2
04:  [ . 1 2 3 4 5 2 ]    [ 1 2 1 1 1 . . ]   2
05:  [ . 1 2 3 4 5 1 ]    [ 2 1 1 1 1 . . ]   2
06:  [ . 1 2 3 4 3 2 ]    [ 1 2 2 1 . . . ]   2
07:  [ . 1 2 3 4 3 1 ]    [ 2 1 2 1 . . . ]   2
08:  [ . 1 2 3 4 2 3 ]    [ 1 2 1 1 . 1 . ]   2
09:  [ . 1 2 3 4 2 1 ]    [ 2 2 1 1 . . . ]   2
10:  [ . 1 2 3 4 1 2 ]    [ 2 1 1 1 . 1 . ]   2
11:  [ . 1 2 3 2 1 2 ]    [ 2 2 1 . . 1 . ]   2
12:  [ . 1 2 3 1 2 1 ]    [ 3 1 1 . 1 . . ]   3
This gives row n=7: [0, 1, 10, 1, 0, 0, ... ].
		

Crossrefs

Columns k=0-10 give: A000007, A000012 (for n>0), A245747, A245748, A245749, A245750, A245751, A245752, A245753, A245754, A245755.
Cf. A004111 (identity trees), A244372 (unlabeled rooted trees by outdegree).

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b(i-1$2, k$2), j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    g:= proc(n) local k; if n=1 then 0 else
           for k while T(n, k)>0 do od; k-1 fi
        end:
    T:= (n, k)-> b(n-1$2, k$2) -`if`(k=0, 0, b(n-1$2, k-1$2)):
    seq(seq(T(n, k), k=0..g(n)), n=1..25);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i<1, 0, Sum[Binomial[b[i-1, i-1, k, k], j]*b[n-i*j, i-1, t-j, k], {j, 0, Min[t, n/i]}]]]; g[n_] := If[ n == 1 , 0, For[k=1, T[n, k]>0 , k++]; k-1]; T[n_, k_] := b[n-1, n-1, k, k] - If[k == 0, 0, b[n-1, n-1, k-1, k-1]]; Table[Table[T[n, k], {k, 0, g[n]}], {n, 1, 25}] // Flatten (* Jean-François Alcover, Feb 11 2015, after Maple *)

A244407 Number of unlabeled rooted trees with 2n nodes and maximal outdegree (branching factor) n.

Original entry on oeis.org

1, 2, 6, 17, 50, 143, 416, 1199, 3474, 10049, 29119, 84377, 244748, 710199, 2062274, 5991418, 17416401, 50652248, 147384676, 429043390, 1249508947, 3640449679, 10610613552, 30937605076, 90237313083, 263288153074, 768449666117, 2243530461067, 6552016136667
Offset: 1

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(2*n-1$2, n$2)-b(2*n-1$2, n-1$2):
    seq(a(n), n=1..30);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[b[i - 1, i - 1, k, k] + j - 1, j]* b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]] // FullSimplify] ; a[n_] := b[2*n - 1, 2 n - 1, n, n] - b[2*n - 1, 2 n - 1, n - 1, n - 1]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 06 2015, after Maple *)

Formula

a(n) = A244372(2n,n).
a(n) ~ c * d^n / sqrt(n), where d = 2.955765285651994974714817524... is the Otter's rooted tree constant (see A051491), and c = 0.9495793... . - Vaclav Kotesovec, Jul 11 2014

A244399 Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 3.

Original entry on oeis.org

1, 2, 6, 16, 43, 113, 300, 787, 2074, 5460, 14391, 37960, 100275, 265187, 702307, 1862463, 4945952, 13152441, 35023003, 93385548, 249330208, 666539949, 1784102735, 4781254117, 12828545419, 34459732110, 92668129050, 249469906115, 672296028786, 1813606782459
Offset: 4

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Column k=3 of A244372.

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(n-1$2, 3$2) -`if`(k=0, 0, b(n-1$2, 2$2)):
    seq(a(n), n=4..35);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i<1, 0, Sum[Binomial[b[i-1, i-1, k, k]+j-1, j]*b[n-i*j, i-1, t-j, k], {j, 0, Min[t, n/i]}]]//FullSimplify]; a[n_] := b[n-1, n-1, 3, 3] - If[n == 0, 0, b[n-1, n-1, 2, 2]]; Table[a[n], {n, 4, 35}] (* Jean-François Alcover, Feb 09 2015, after Maple *)

Formula

a(n) = A000598(n) - A001190(n+1) = A000598(n) - A036656(n+1).
a(n) ~ c * d^n / n^(3/2), where d = 1/A261340 = 2.81546003317615... and c = 0.5178759064... . - Vaclav Kotesovec, Jun 27 2014

A244410 Number of unlabeled rooted trees with 2n+1 nodes and maximal outdegree (branching factor) n.

Original entry on oeis.org

1, 1, 5, 16, 49, 142, 415, 1198, 3473, 10048, 29118, 84376, 244747, 710198, 2062273, 5991417, 17416400, 50652247, 147384675, 429043389, 1249508946, 3640449678, 10610613551, 30937605075, 90237313082, 263288153073, 768449666116, 2243530461066, 6552016136666
Offset: 0

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> `if`(n=0, 1, b(2*n$2, n$2)-b(2*n$2, n-1$2)):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[b[i - 1, i - 1, k, k] + j - 1, j]* b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]] // FullSimplify] ; a[n_] := If[n == 0, 1, b[2*n, 2 n, n, n] - b[2*n, 2 n, n - 1, n - 1]]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Feb 06 2015, after Maple *)

Formula

a(n) = A244372(2n+1,n).
a(n) ~ c * d^n / sqrt(n), where d = 2.955765285651994974714817524... is the Otter's rooted tree constant (see A051491), and c = 2.806733... . - Vaclav Kotesovec, Jul 11 2014

A244398 Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 2.

Original entry on oeis.org

1, 2, 5, 10, 22, 45, 97, 206, 450, 982, 2178, 4849, 10904, 24630, 56010, 127911, 293546, 676156, 1563371, 3626148, 8436378, 19680276, 46026617, 107890608, 253450710, 596572386, 1406818758, 3323236237, 7862958390, 18632325318, 44214569099, 105061603968
Offset: 3

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Column k=2 of A244372.

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(n-1$2, 2$2) -`if`(n=0, 0, 1):
    seq(a(n), n=3..40);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i<1, 0, Sum[Binomial[b[i-1, i-1, k, k]+j-1, j]*b[n-i*j, i-1, t-j, k], {j, 0, Min[t, n/i]}]] // FullSimplify]; a[n_] := b[n-1, n-1, 2, 2] - If[n == 0, 0, 1]; Table[a[n], {n, 3, 40}] (* Jean-François Alcover, Feb 09 2015, after Maple *)

Formula

a(n) = A001190(n+1)-1 = A036656(n+1)-1.
a(n) ~ c * d^n / n^(3/2), where d = 2.4832535361726368... = A086317 and c = 0.7916031835775118... = A086318. - Vaclav Kotesovec, Jun 27 2014

A244400 Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 4.

Original entry on oeis.org

1, 2, 6, 17, 49, 136, 386, 1081, 3044, 8549, 24052, 67642, 190426, 536205, 1510920, 4259418, 12014682, 33907056, 95740913, 270468869, 764450150, 2161638413, 6115252839, 17307553766, 49005101669, 138811296158, 393351362321, 1115072623713, 3162183392471
Offset: 5

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Column k=4 of A244372.

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(n-1$2, 4$2) -`if`(k=0, 0, b(n-1$2, 3$2)):
    seq(a(n), n=5..40);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[b[i - 1, i - 1, k, k] + j - 1, j]* b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]] // FullSimplify]; a[n_] := b[n-1, n-1, 4, 4] - If[n == 0, 0, b[n-1, n-1, 3, 3]]; Table[a[n], {n, 5, 40}] (* Jean-François Alcover, Feb 09 2015, after Maple *)

Formula

a(n) = A036718(n) - A000598(n).

A244401 Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 5.

Original entry on oeis.org

1, 2, 6, 17, 50, 142, 409, 1169, 3356, 9617, 27601, 79210, 227527, 653793, 1879867, 5407806, 15564968, 44820889, 129127761, 372177974, 1073169150, 3095721985, 8933568154, 25789862435, 74477871565, 215155604291, 621754458752, 1797297119000, 5196966140656
Offset: 6

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Column k=5 of A244372.

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(n-1$2, 5$2) -`if`(k=0, 0, b(n-1$2, 4$2)):
    seq(a(n), n=6..40);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[b[i - 1, i - 1, k, k] + j - 1, j]* b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]] // FullSimplify] ; a[n_] := b[n-1, n-1, 5, 5] - If[n == 0, 0, b[n-1, n-1, 4, 4]]; Table[a[n], {n, 6, 40}] (* Jean-François Alcover, Feb 09 2015, after Maple *)

Formula

a(n) = A036721(n) - A036718(n).

A244402 Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 6.

Original entry on oeis.org

1, 2, 6, 17, 50, 143, 415, 1192, 3444, 9931, 28687, 82857, 239563, 692878, 2005381, 5806915, 16824277, 48767953, 141430699, 410341703, 1191064873, 3458607705, 10046993035, 29196507434, 84874753458, 246814998803, 717965190047, 2089140528083, 6080768466919
Offset: 7

Views

Author

Joerg Arndt and Alois P. Heinz, Jun 27 2014

Keywords

Crossrefs

Column k=6 of A244372.

Programs

  • Maple
    b:= proc(n, i, t, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(binomial(b((i-1)$2, k$2)+j-1, j)*
           b(n-i*j, i-1, t-j, k), j=0..min(t, n/i))))
        end:
    a:= n-> b(n-1$2, 6$2) -`if`(k=0, 0, b(n-1$2, 5$2)):
    seq(a(n), n=7..40);
  • Mathematica
    b[n_, i_, t_, k_] := b[n, i, t, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[b[i - 1, i - 1, k, k] + j - 1, j]* b[n - i*j, i - 1, t - j, k], {j, 0, Min[t, n/i]}]] // FullSimplify] ; a[n_] := b[n - 1, n - 1, 6, 6] - If[n == 0, 0, b[n - 1, n - 1, 5, 5]]; Table[a[n], {n, 7, 40}] (* Jean-François Alcover, Feb 09 2015, after Maple *)

Formula

a(n) = A036722(n) - A036721(n).
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