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 1-9 of 9 results.

A365150 G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x))^3.

Original entry on oeis.org

1, 1, 5, 26, 150, 925, 5967, 39772, 271758, 1893431, 13400897, 96078789, 696333585, 5093266409, 37549674939, 278739057687, 2081637677823, 15628794649931, 117897848681271, 893167062280029, 6792410218680749, 51835002735642287, 396821349652564273
Offset: 0

Views

Author

Seiichi Manyama, Aug 23 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=3, t=1) = sum(k=0, n, binomial(t*(n+k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n+k+1));

Formula

If g.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^s )^t, then a(n) = Sum_{k=0..n} binomial(t*(n+k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n+k+1).
G.f.: (1/x) * Series_Reversion( x*(1 - x/(1 - x)^3) ). - Seiichi Manyama, Sep 24 2024

A193589 Augmentation of the Fibonacci triangle A193588. See Comments.

Original entry on oeis.org

1, 1, 2, 1, 4, 7, 1, 6, 18, 31, 1, 8, 33, 90, 154, 1, 10, 52, 185, 481, 820, 1, 12, 75, 324, 1065, 2690, 4575, 1, 14, 102, 515, 2006, 6276, 15547, 26398, 1, 16, 133, 766, 3420, 12468, 37711, 92124, 156233, 1, 18, 168, 1085, 5439, 22412, 78030, 230277
Offset: 0

Views

Author

Clark Kimberling, Jul 31 2011

Keywords

Comments

For an introduction to the unary operation augmentation as applied to triangular arrays or sequences of polynomials, see A193091.
Regarding A193589, if the triangle is written as (w(n,k)), then w(n,n)=A007863(n); w(n,n-1)=A011270; and
(col 3)=A033537.

Examples

			First 5 rows of A193588:
1
1....2
1....2....3
1....2....3....5
1....2....3....5....8
First 5 rows of A193589:
1
1....2
1....4....7
1....6....18...31
1....8....33...90...154
		

Crossrefs

Programs

  • Mathematica
    p[n_, k_] := Fibonacci[k + 2]
    Table[p[n, k], {n, 0, 5}, {k, 0, n}]  (* A193588 *)
    m[n_] := Table[If[i <= j, p[n + 1 - i, j - i], 0], {i, n}, {j, n + 1}]
    TableForm[m[4]]
    w[0, 0] = 1; w[1, 0] = p[1, 0]; w[1, 1] = p[1, 1];
    v[0] = w[0, 0]; v[1] = {w[1, 0], w[1, 1]};
    v[n_] := v[n - 1].m[n]
    TableForm[Table[v[n], {n, 0, 6}]]  (* A193589 *)
    Flatten[Table[v[n], {n, 0, 8}]]

A367232 G.f. satisfies A(x) = 1 + x*A(x)^3 / (1 - x*A(x))^2.

Original entry on oeis.org

1, 1, 5, 29, 189, 1325, 9757, 74429, 583037, 4662653, 37911037, 312457469, 2604534269, 21919435517, 185992729085, 1589480795133, 13668519794685, 118188894992381, 1026965424910333, 8962634482450429, 78528344593006589, 690502653622083581
Offset: 0

Views

Author

Seiichi Manyama, Nov 11 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=2, t=3, u=1) = sum(k=0, n, binomial(t*k+u*(n-k)+1, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+1));

Formula

If g.f. satisfies A(x) = 1 + x*A(x)^t / (1 - x*A(x)^u)^s, then a(n) = Sum_{k=0..n} binomial(t*k+u*(n-k)+1,k) * binomial(n+(s-1)*k-1,n-k) / (t*k+u*(n-k)+1).

A011272 Hybrid binary rooted trees with n nodes whose root is labeled by "a".

Original entry on oeis.org

0, 1, 3, 13, 64, 339, 1885, 10851, 64109, 386510, 2368354, 14706331, 92337618, 585239903, 3739309053, 24059542845, 155756019048, 1013801283133, 6630587014935, 43553555324502
Offset: 0

Views

Author

Jean Pallo (pallo(AT)u-bourgogne.fr)

Keywords

Formula

a(n) = A007863(n) - A011270(n).

A367234 G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x))^4.

Original entry on oeis.org

1, 1, 6, 35, 226, 1561, 11276, 84150, 643730, 5021038, 39781858, 319282210, 2590312872, 21208628405, 175024439504, 1454329099044, 12157356271998, 102170610282040, 862721635191860, 7315768816166027, 62274763166575410, 531950072655682896, 4558282056420235664
Offset: 0

Views

Author

Seiichi Manyama, Nov 11 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=4, t=2, u=1) = sum(k=0, n, binomial(t*k+u*(n-k)+1, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+1));

Formula

If g.f. satisfies A(x) = 1 + x*A(x)^t / (1 - x*A(x)^u)^s, then a(n) = Sum_{k=0..n} binomial(t*k+u*(n-k)+1,k) * binomial(n+(s-1)*k-1,n-k) / (t*k+u*(n-k)+1).
From Seiichi Manyama, Dec 01 2024: (Start)
G.f.: exp( Sum_{k>=1} A378567(k) * x^k/k ).
a(n) = (1/(n+1)) * [x^n] 1/(1 - x/(1 - x)^4)^(n+1).
G.f.: (1/x) * Series_Reversion( x*(1 - x/(1 - x)^4) ). (End)

A378565 a(n) = Sum_{k=0..n} binomial(n+k-1,k) * binomial(n+k-1,n-k).

Original entry on oeis.org

1, 1, 7, 43, 271, 1746, 11425, 75615, 504799, 3392953, 22930282, 155664356, 1060710457, 7250779238, 49700101101, 341474150583, 2351032782783, 16216401440106, 112035931072915, 775163096510445, 5370301986029066, 37249469056575504, 258648802856972348
Offset: 0

Views

Author

Seiichi Manyama, Dec 01 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n+k-1, k] * Binomial[n+k-1, 2*k-1], {k, 0, n}], {n, 0, 25}] (* Vaclav Kotesovec, Dec 01 2024 *)
  • PARI
    a(n) = sum(k=0, n, binomial(n+k-1, k)*binomial(n+k-1, n-k));

Formula

a(n) = [x^n] 1/(1 - x/(1 - x)^2)^n.
a(n) ~ (525 - 32*210^(2/3)/(157*sqrt(105) - 1575)^(1/3) + 4*(210*(157*sqrt(105) - 1575))^(1/3))^(1/6) * ((36 + (1208682 - 28350*sqrt(105))^(1/3)/3 + (6*(7461 + 175*sqrt(105)))^(1/3))^n / (2^(2/3) * 7^(1/3) * sqrt(Pi*n) * 3^(n + 1/6) * 5^(n + 1/3))). - Vaclav Kotesovec, Dec 01 2024

A011274 Triangle of numbers of hybrid rooted trees (divided by Fibonacci numbers).

Original entry on oeis.org

1, 2, 1, 7, 4, 1, 31, 18, 6, 1, 154, 90, 33, 8, 1, 820, 481, 185, 52, 10, 1, 4575, 2690, 1065, 324, 75, 12, 1, 26398, 15547, 6276, 2006, 515, 102, 14, 1, 156233, 92124, 37711, 12468, 3420, 766, 133, 16, 1, 943174, 556664, 230277, 78030, 22412, 5439, 1085, 168, 18, 1
Offset: 1

Views

Author

Jean Pallo (pallo(AT)u-bourgogne.fr)

Keywords

Comments

Triangle T(n,k) = [x^(n-k)] A(x)^k where A(x) is the o.g.f. of A007863. - Vladimir Kruchinin, Mar 17 2011
Riordan array (f(x), x*f(x)) where f(x) is the g.f. of A007863. - Philippe Deléham, Feb 03 2014

Examples

			     1
     2    1
     7    4    1
    31   18    6   1
   154   90   33   8  1
   820  481  185  52 10  1
  4575 2690 1065 324 75 12 1
Production matrix is:
   2   1
   3   2   1
   5   3   2   1
   8   5   3   2   1
  13   8   5   3   2   1
  21  13   8   5   3   2   1
  34  21  13   8   5   3   2   1
  55  34  21  13   8   5   3   2   1
  89  55  34  21  13   8   5   3   2   1
  ... - _Philippe Deléham_, Feb 03 2014
		

Crossrefs

Programs

  • Maple
    A011274 := proc(n,k) k/n*add( binomial(i+n-1,n-1)*binomial(i+n,n-k-i),i=0..n-k) ; end proc: # R. J. Mathar, Mar 21 2011
  • Mathematica
    t[n_, k_] := k/n*Binomial[n, k]*HypergeometricPFQ[ {k-n, n, n+1}, {1/2 + k/2, 1+k/2}, -1/4]; Flatten[ Table[ t[n, k], {n, 1, 10}, {k, 1, n}]] (* Jean-François Alcover, Dec 02 2011, after Vladimir Kruchinin *)
  • Maxima
    A011274(n,k):= k/n*sum(binomial(i+n-1,n-1)*binomial(i+n,n-k-i), i,0,n-k); /* Vladimir Kruchinin, Mar 17 2011 */

Formula

T(n,k) = (k/n) *Sum_{i=0..n-k} binomial(i+n-1,n-1)*binomial(i+n,n-k-i). - Vladimir Kruchinin, Mar 17 2011
(r/(m*n+r))*T((m+1)*n+r,m*n+r) = Sum_{k=1..n} k*T((m+1)*n-k,m*n)*T(r+k,r)/n. - Vladimir Kruchinin, Mar 17 2011
T(n,m) = (m/n)*Sum_{k=1..n-m+1} k*A007863(k-1)*T(n-k,m-1), 1 < m <= n. - Vladimir Kruchinin, Mar 17 2011

A365148 G.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^2 )^2.

Original entry on oeis.org

1, 2, 13, 102, 898, 8484, 84061, 861918, 9068950, 97366812, 1062425010, 11747773372, 131350499044, 1482494173128, 16867912278237, 193273940978574, 2228186999313678, 25827663921909228, 300825086742672934, 3519001122784601524, 41325186203051759324
Offset: 0

Views

Author

Seiichi Manyama, Aug 23 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=2, t=2) = sum(k=0, n, binomial(t*(n+k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n+k+1));

Formula

If g.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^s )^t, then a(n) = Sum_{k=0..n} binomial(t*(n+k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n+k+1).

A365149 G.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^2 )^3.

Original entry on oeis.org

1, 3, 27, 301, 3780, 51030, 723170, 10611594, 159845946, 2457515235, 38406398016, 608330707740, 9744053489754, 157564967282709, 2568706865998272, 42173100349112852, 696692754641035014, 11572241797209975966, 193153224033985241217
Offset: 0

Views

Author

Seiichi Manyama, Aug 23 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=2, t=3) = sum(k=0, n, binomial(t*(n+k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n+k+1));

Formula

If g.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^s )^t, then a(n) = Sum_{k=0..n} binomial(t*(n+k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n+k+1).
Showing 1-9 of 9 results.