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.

User: Cedric Chauve

Cedric Chauve's wiki page.

Cedric Chauve has authored 12 sequences. Here are the ten most recent ones:

A307942 Number of evolutionary duplication-loss-histories of the complete binary species tree with 8 leaves.

Original entry on oeis.org

8, 148, 3376, 89390, 2624872, 82866636, 2755019736, 95135709027, 3380416782760, 122798718575216, 4539685792433848, 170225552910292438, 6458330316575589176, 247456381334355675220, 9561546562984390785960, 372141845574597078971490, 14575950501012888889866120
Offset: 1

Author

Cedric Chauve, May 07 2019

Keywords

Comments

An evolutionary history of size n is an ordered rooted (incomplete) binary tree with n leaves describing the evolution of a gene family of a species in phylogenomics. The complete binary species tree S of size k is a complete binary tree with k leaves. Any node of the history is associated to a unique node of S, where specifically every leaf is associated to a leaf of S. A history is created by the following process (note that intermediate trees in this process may not be valid histories): Start with a root node associated to the root of S. For a given tree in the growth process, choose a leaf and perform a duplication, speciation, or (speciation-)loss event. A duplication event creates two children both associated to the same node as its parent. A speciation or (speciation-)loss event can only occur if the node is associated to an internal node in S. In that case, a speciation event creates two children associated to the children of the node in S. A (speciation-)loss event creates only a left or right child, associated to the left or right child in S, respectively.

Examples

			See A307941 (complete binary species tree with 4 leaves).
		

Crossrefs

Cf. A000108 (caterpillar/complete binary species tree with 1 leaf, ordinary binary trees).
Cf. A307696, A307697, A307698, A307700 (caterpillar species tree with 2, 3, 4, 5 leaves).

Programs

  • PARI
    z='z+O('z^20); my(t = sqrt(1-4*z), u = sqrt(-5+6*t+4*z), v = sqrt(1+6*u-6*t-4*z)); Vec(1/2-(1/2)*sqrt(-5+6*v-6*u+6*t+4*z)) \\ Jianing Song, Jul 29 2019

Formula

G.f.: 1/2-(1/2)*sqrt(-5+6*v-6*u+6*t+4*z) where t = sqrt(1-4*z), u = sqrt(-5+6*t+4*z) and v = sqrt(1+6*u-6*t-4*z).

A307943 Number of evolutionary duplication-loss-histories of the complete binary species tree with 16 leaves.

Original entry on oeis.org

16, 616, 28832, 1556780, 93017264, 5971377672, 403667945712, 28346017000314, 2048467088599520, 151362953286590792, 11383212160213595696, 868385902978402717696, 67032303753464250574432, 5225869642113491897295040, 410865063418648682500317120
Offset: 1

Author

Cedric Chauve, May 07 2019

Keywords

Comments

An evolutionary history of size n is an ordered rooted (incomplete) binary tree with n leaves describing the evolution of a gene family of a species in phylogenomics. The complete binary species tree S of size k is a complete binary tree with k leaves. Any node of the history is associated to a unique node of S, where specifically every leaf is associated to a leaf of S. A history is created by the following process (note that intermediate trees in this process may not be valid histories): Start with a root node associated to the root of S. For a given tree in the growth process, choose a leaf and perform a duplication, speciation, or (speciation-)loss event. A duplication event creates two children both associated to the same node as its parent. A speciation or (speciation-)loss event can only occur if the node is associated to an internal node in S. In that case, a speciation event creates two children associated to the children of the node in S. A (speciation-)loss event creates only a left or right child, associated to the left or right child in S, respectively.

Examples

			See A307941 (complete binary species tree with 4 leaves).
		

Crossrefs

Cf. A000108 (caterpillar/complete binary species tree with 1 leaf, ordinary binary trees).
Cf. A307696, A307697, A307698, A307700 (caterpillar species tree with 2, 3, 4, 5 leaves).

Formula

G.f.: 1/2-(1/2)*sqrt(1-6*v+6*w+6*u-6*t-4*z) where t = sqrt(1-4*z), u = sqrt(-5+6*t+4*z), v = sqrt(1+6*u-6*t-4*z) and w = sqrt(-5+6*v-6*u+6*t+4*z)

A307941 Number of evolutionary duplication-loss-histories of the complete binary species tree with 4 leaves.

Original entry on oeis.org

4, 34, 368, 4685, 66416, 1013268, 16279788, 271594611, 4660794200, 81747301898, 1458812278424, 26400987754054, 483374731032868, 8936983620559660, 166617056922535080, 3128790129161470470, 59124052722375912960, 1123458655726125274620, 21452847767668402271220
Offset: 1

Author

Cedric Chauve, May 07 2019

Keywords

Comments

An evolutionary history of size n is an ordered rooted (incomplete) binary tree with n leaves describing the evolution of a gene family of a species in phylogenomics. The complete binary species tree S of size k is a complete binary tree with k leaves. Any node of the history is associated to a unique node of S, where specifically every leaf is associated to a leaf of S. A history is created by the following process (note that intermediate trees in this process may not be valid histories): Start with a root node associated to the root of S. For a given tree in the growth process, choose a leaf and perform a duplication, speciation, or (speciation-)loss event. A duplication event creates two children both associated to the same node as its parent. A speciation or (speciation-)loss event can only occur if the node is associated to an internal node in S. In that case, a speciation event creates two children associated to the children of the node in S. A (speciation-)loss event creates only a left or right child, associated to the left or right child in S, respectively.

Examples

			The complete binary species tree with 4 leaves is equal to
     a
   /   \
  b     c
/ \   / \
1   2  3  4
For convenience the internal nodes are labeled by a,b,c and the leaves by 1,2,3,4. The associated nodes in the histories will be denoted by the same labels.
The a(1)=4 histories with n=1 leaf are created by the following growth process:
    a     a     a      a
   /     /       \      \
  b     b         c      c
/       \       /        \
1         2     3          4
after two loss events each.
		

Crossrefs

Cf. A000108 (caterpillar/complete binary species tree with 1 leaf, ordinary binary trees).
Cf. A307696, A307697, A307698, A307700 (caterpillar species tree with 2, 3, 4, 5 leaves).

Programs

  • PARI
    z='z+O('z^20); Vec(1/2-(1/2)*sqrt(1+6*sqrt(-5+6*sqrt(1-4*z)+4*z)-6*sqrt(1-4*z)-4*z)) \\ Jianing Song, Jul 29 2019

Formula

G.f.: 1/2-(1/2)*sqrt(1+6*sqrt(-5+6*sqrt(1-4*z)+4*z)-6*sqrt(1-4*z)-4*z).

A071212 Number of labeled cyclic trees with n nodes such that the root is smaller than all its children.

Original entry on oeis.org

1, 4, 28, 286, 3848, 64198, 1277400, 29507784, 775826832, 22869156168, 746817076080, 26758697374176, 1043610018593088, 44007103062886416, 1994973101346054144, 96747604119630501120, 4997654990315699224320
Offset: 2

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

References

  • C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, research report RR-1226-99, LaBRI, Bordeaux I University, 1999.

Crossrefs

Cf. A000312.

Programs

  • Maple
    n -> sum((n! / (n-k)!) * (-1)^(n-1-k) * stirling1(n-1, k), k=0..n) - sum(((n-2)! / (n-1-k)!) * (-1)^(n-k) * stirling1(n, k), k=0..n-1);

A071211 Triangular array T(n,k) read by rows, giving number of labeled free trees such that the root is smaller than all its children, with respect to the number n of vertices and to the label k of the root.

Original entry on oeis.org

1, 3, 1, 16, 8, 3, 125, 75, 40, 16, 1296, 864, 540, 300, 125, 16807, 12005, 8232, 5292, 3024, 1296, 262144, 196608, 143360, 100352, 65856, 38416, 16807, 4782969, 3720087, 2834352, 2099520, 1492992, 995328, 589824, 262144, 100000000
Offset: 1

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

References

  • C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, Proceedings of FPSAC/SFCA 2000 (Moscow), Springer, pp. 146-157.

Crossrefs

Cf. A000312, A000272 (first column).

Programs

  • Maple
    T:= (n, k)-> (n-k)*(n+1)^(n-k-1)*n^(k-1):
    seq(seq(T(n, k), k=0..n-1), n=1..10);
  • PARI
    tabl(nn) = {for (n=1, nn, for (k=0, n-1, print1((n-k)*(n+1)^(n-k-1)*n^(k-1), ", ");); print(););} \\ Michel Marcus, Jun 27 2013

Formula

T(n,k) = (n-k)*(n+1)^(n-k-1)*n^(k-1).

A071210 Triangular array T(n,k) read by rows, giving number of labeled free trees such that the root is smaller than all its children, with respect to the number n of vertices and to the degree k of the root.

Original entry on oeis.org

1, 3, 1, 18, 8, 1, 160, 80, 15, 1, 1875, 1000, 225, 24, 1, 27216, 15120, 3780, 504, 35, 1, 470596, 268912, 72030, 10976, 980, 48, 1, 9437184, 5505024, 1548288, 258048, 26880, 1728, 63, 1, 215233605, 127545840, 37200870, 6613488, 765450, 58320
Offset: 1

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

Crossrefs

Cf. A000312, A052182 (first column).

Programs

  • Maple
    (n,k) -> binomial(n+1,k+1)*k*n^(n-k-1)
  • PARI
    tabl(nn) = for (n=1, nn, for (k=1, n, print1(binomial(n+1, k+1)*k*n^(n-k-1), ", ");); print) \\ Michel Marcus, Jun 27 2013

Formula

T(n,k) = binomial(n+1, k+1)*k*n^(n-k-1).

A071209 Triangular array T(n,k) read by rows, giving number of labeled free trees such that the root is smaller than all its children, with respect to the number n of vertices and to the size k of the subtree rooted at the vertex labeled by 1.

Original entry on oeis.org

0, 1, 1, 0, 3, 8, 3, 0, 16, 81, 32, 18, 0, 125, 1024, 405, 240, 160, 0, 1296, 15625, 6144, 3645, 2560, 1875, 0, 16807, 279936, 109375, 64512, 45360, 35000, 27216, 0, 262144, 5764801, 2239488, 1312500, 917504, 708750, 580608, 470596, 0, 4782969
Offset: 1

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

References

  • C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, Proceedings of FPSAC/SFCA 2000 (Moscow), Springer, pp. 146-157.

Crossrefs

Cf. A000312.

Programs

  • Maple
    (n,k) -> binomial(n,k-1)*k^(k-2)*(n-k)^(n+1-k);
  • PARI
    tabl(nn) = {for (n=1, nn, for (k=1, n, print1(binomial(n, k-1)*k^(k-2)*(n-k)^(n+1-k), ", ");); print(););} \\ Michel Marcus, Jun 27 2013

Formula

binomial(n, k-1)*k^(k-2)*(n-k)^(n+1-k)

A071213 Number of labeled planar trees with n nodes such that the root is smaller than all its children.

Original entry on oeis.org

1, 4, 34, 436, 7428, 157368, 3980688, 116949600, 3911421600, 146673662400, 6093249563520, 277729608280320, 13778539159795200, 739059210587980800, 42615627311477606400, 2628646012982829772800, 172704619437756321484800
Offset: 2

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

Crossrefs

Programs

  • Maple
    n -> 2 * sum((n-1) * (n-2+k)! / (k! * (n-1-k)), k=0 .. n-2) - ((2*n-3)! / (n-2)!);
  • Maxima
    C(x):=(1-sqrt(1-4*x))/(2);
    F(x):=1+log(1-x)/x-log(1-x);
    makelist(n!*coeff(taylor(F(C(x))+x*diff(F(C(x)),x),x,0,15),x,n),n,1,15); /*Vladimir Kruchinin, Mar 23 2016 */

Formula

E.g.f.: F(C(x))+x*[F(C(x))]', where C(x)/x is g.f. of Catalan numbers (A000108), F(x)=1+log(1-x)/x-log(1-x). - Vladimir Kruchinin, Mar 23 2016

A071214 Number of labeled ordered trees with n nodes such that the root is smaller than all its children.

Original entry on oeis.org

1, 5, 46, 614, 10716, 230712, 5903472, 174942000, 5890370400, 222069752640, 9265980286080, 423888544154880, 21094789126924800, 1134492559101619200, 65567415318776985600, 4052502049455940147200, 266725354163752808755200, 18624661769541550593024000
Offset: 2

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

References

  • C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, research report RR-1226-99, LaBRI, Bordeaux I University, 1999.

Crossrefs

Programs

  • Maple
    a:= n -> ((2*n-2)! / (n-1)!) - sum((n+k-1)! / ((n-k-1)*k!), k=0 .. n-2):
    seq(a(n), n=2..22);

Formula

From Vladimir Kruchinin, Jun 02 2016: (Start)
E.g.f.: -[(log(1-x*C(x)))/C(x)]', where C(x) is g.f. of Catalan numbers (A000108).
a(n) = ((n+1)!*Sum_{k=1..n} ((k*binomial(2*n-k-1,n-k))/(k+1)))/n. (End)

A071207 Triangular array T(n,k) read by rows, giving number of rooted trees on the vertex set {1..n+1} where k children of the root have a label smaller than the label of the root.

Original entry on oeis.org

1, 1, 1, 4, 4, 1, 27, 27, 9, 1, 256, 256, 96, 16, 1, 3125, 3125, 1250, 250, 25, 1, 46656, 46656, 19440, 4320, 540, 36, 1, 823543, 823543, 352947, 84035, 12005, 1029, 49, 1, 16777216, 16777216, 7340032, 1835008, 286720, 28672, 1792, 64, 1, 387420489
Offset: 0

Author

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

Keywords

Comments

The n-th term of the n-th binomial transform of a sequence {b} is given by {d} where d(n) = sum(k=0,n,T(n,k)*b(k)) and T(n,k)=binomial(n,k)*n^(n-k); such diagonals are related to the hyperbinomial transform (A088956). - Paul D. Hanna, Nov 04 2003
T(n,k) gives the number of divisors of A181555(n) with (n-k) distinct prime factors. See also A001221, A146289, A146290, A181567. - Matthew Vandermast, Oct 31 2010
T(n,k) is the number of partial functions on {1,2,...,n} leaving exactly k elements undefined. Row sums = A000169. - Geoffrey Critzer, Jan 08 2012
As a triangular matrix, transforms rows into diagonals in the table of coefficients of successive iterations of x/(1-x). - Paul D. Hanna, Jan 19 2014
Also the number of rooted trees on n+1 labeled vertices in which some specified vertex (say, vertex 1) has k children. - Alan Sokal, Jul 22 2022

Examples

			1
1     1
4     4     1
27    27    9     1
256   256   96    16    1
3125  3125  1250  250   25    1
46656 46656 19440 4320  540   36    1
		

Crossrefs

Programs

  • Maple
    T:= (n, k)-> binomial(n, k)*n^(n-k): seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    Prepend[Flatten[ Table[Table[Binomial[n, k] n^(n - k), {k, 0, n}], {n, 1, 8}]], 1]  (* Geoffrey Critzer, Jan 08 2012 *)
  • PARI
    T(n,k)=if(k<0 || k>n,0,binomial(n,k)*n^(n-k))
    
  • PARI
    /* Transforms rows into diagonals in the iterations of x/(1-x): */
    {T(n, k)=local(F=x, M, N, P, m=n); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x/(1-x+x*O(x^(m+2))))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, F=x; for(i=1, r, F=subst(F, x, x/(1-x+x*O(x^(m+2))))); polcoeff(F, c)); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, k+1]}
    for(n=0, 10, for(k=0, n, print1(T(n, k), ", ")); print("")) \\ Paul D. Hanna, Jan 19 2014

Formula

T(n,k) = binomial(n, k)*n^(n-k).
E.g.f.: (-LambertW(-y)/y)^x/(1+LambertW(-y)). - Vladeta Jovovic

Extensions

Name edited by Alan Sokal, Jul 22 2022