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

A364747 G.f. A(x) satisfies A(x) = 1 + x*A(x)^4 / (1 - x*A(x)).

Original entry on oeis.org

1, 1, 5, 32, 234, 1854, 15490, 134380, 1198944, 10931761, 101412677, 954155059, 9083120975, 87326765375, 846709605539, 8269910074087, 81291388929027, 803592049667495, 7983612883739843, 79671910265120574, 798283229227457304, 8027625597750959053
Offset: 0

Views

Author

Seiichi Manyama, Aug 05 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = if(n==0, 1, sum(k=0, n-1, binomial(n, k)*binomial(4*n-3*k, n-1-k))/n);
    
  • PARI
    a(n, r=1, s=1, t=4, u=1) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+r)); \\ Seiichi Manyama, Dec 05 2024

Formula

a(n) = (1/n) * Sum_{k=0..n-1} binomial(n,k) * binomial(4*n-3*k,n-1-k) for n > 0.
From Seiichi Manyama, Dec 05 2024: (Start)
G.f. A(x) satisfies A(x) = 1/(1 - x*A(x)^3/(1 - x*A(x))).
If g.f. satisfies A(x) = ( 1 + x*A(x)^(t/r) / (1 - x*A(x)^(u/r))^s )^r, then a(n) = r * Sum_{k=0..n} binomial(t*k+u*(n-k)+r,k) * binomial(n+(s-1)*k-1,n-k)/(t*k+u*(n-k)+r). (End)

A336573 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) = (-1)^n * Sum_{j=0..n} (-2)^j * binomial(n,j) * binomial(k*n+j+1,n)/(k*n+j+1).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 4, 1, 1, 4, 11, 8, 1, 1, 5, 21, 45, 16, 1, 1, 6, 34, 126, 197, 32, 1, 1, 7, 50, 267, 818, 903, 64, 1, 1, 8, 69, 484, 2279, 5594, 4279, 128, 1, 1, 9, 91, 793, 5105, 20540, 39693, 20793, 256, 1, 1, 10, 116, 1210, 9946, 56928, 192350, 289510, 103049, 512
Offset: 0

Views

Author

Seiichi Manyama, Jul 26 2020

Keywords

Comments

T(n,k) is the number of Sylvester classes of k-packed words of degree n.

Examples

			Square array begins:
   1,   1,   1,    1,    1,    1, ...
   1,   1,   1,    1,    1,    1, ...
   2,   3,   4,    5,    6,    7, ...
   4,  11,  21,   34,   50,   69, ...
   8,  45, 126,  267,  484,  793, ...
  16, 197, 818, 2279, 5105, 9946, ...
		

Crossrefs

Columns k = 0-5 are: A011782, A001003, A003168, A243659, A243667, A243668.
Main diagonal is A336495.

Programs

  • Maple
    T := (n,k) -> `if`(k=0, `if`(n=0, 1, 2^(n-1)), (-1)^n*(binomial(k*n+1, n)* hypergeom([-n, k*n+1], [(k-1)*n+2], 2)) / (k*n+1)):
    seq(lprint(seq(simplify(T(n, k)), k=0..9)), n=0..6); # Peter Luschny, Jul 26 2020
  • Mathematica
    T[n_, k_] := (-1)^n * Sum[(-2)^j * Binomial[n, j] * Binomial[k*n+j+1, n]/(k*n+j+1), {j, 0, n}]; Table[T[k, n-k], {n, 0, 10}, {k, 0, n}] // Flatten (* Amiram Eldar, May 01 2021 *)
  • PARI
    T(n, k) = (-1)^n*sum(j=0, n, (-2)^j*binomial(n, j)*binomial(k*n+j+1, n)/(k*n+j+1));
    
  • PARI
    T(n, k) = my(A=1+x*O(x^n)); for(i=0, n, A=1-x*A^k*(1-2*A)); polcoeff(A, n);
    
  • PARI
    T(n, k) = (-1)^n*sum(j=0, n, (-2)^(n-j)*binomial(k*n+1, j)*binomial((k+1)*n-j, n-j))/(k*n+1);

Formula

G.f. A_k(x) of column k satisfies A_k(x) = 1 - x * A_k(x)^k * (1 - 2 * A_k(x)).
T(n,k) = ( (-1)^n / (k*n+1) ) * Sum_{j=0..n} (-2)^(n-j) * binomial(k*n+1,j) * binomial((k+1)*n-j,n-j).
T(n,k) = (-1)^n*binomial(k*n+1, n)*hypergeom([-n, k*n+1], [(k-1)*n+2], 2)/(k*n+1) for k >= 1. - Peter Luschny, Jul 26 2020
T(n,k) = (1/n) * Sum_{j=0..n-1} binomial(n,j) * binomial((k+1)*n-j,n-1-j) for n > 0. - Seiichi Manyama, Aug 08 2023

A369012 Expansion of (1/x) * Series_Reversion( x * (1-x/(1-x))^3 ).

Original entry on oeis.org

1, 3, 18, 133, 1095, 9636, 88718, 843993, 8230671, 81841987, 826641816, 8457710604, 87472494564, 912995025912, 9604763388534, 101736967518497, 1084125909550959, 11614159795566489, 125011746270524690, 1351312626871871661, 14662950224977228047
Offset: 0

Views

Author

Seiichi Manyama, Jan 11 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x/(1-x))^3)/x)
    
  • PARI
    a(n, s=1, t=3, u=-3) = sum(k=0, n\s, binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);

Formula

a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(3*n+k+2,k) * binomial(n-1,n-k).
D-finite with recurrence 96*(3*n+2)*(3*n+1)*(n+1)*a(n) +4*(-4121*n^3 +1922*n^2 -1273*n+124)*a(n-1) +4*(20588*n^3 -76648*n^2 +98677*n -43586)*a(n-2) +(-90073*n^3 +671565*n^2 -1665278*n +1375320)*a(n-3) +210*(n-4)*(3*n-7) *(3*n-8)*a(n-4)=0. - R. J. Mathar, Jan 25 2024
From Seiichi Manyama, Dec 02 2024: (Start)
G.f.: exp( Sum_{k>=1} A378612(k) * x^k/k ).
a(n) = (1/(n+1)) * [x^n] 1/(1 - x/(1 - x))^(3*(n+1)).
G.f.: B(x)^3 where B(x) is the g.f. of A243659.
a(n) = 3 * Sum_{k=0..n} 2^k * (-1)^(n-k) * binomial(n,k) * binomial(3*n+k+3,n)/(3*n+k+3). (End)

A364923 G.f. satisfies A(x) = 1 + x*A(x)^4 / (1 - 2*x*A(x)^3).

Original entry on oeis.org

1, 1, 6, 48, 442, 4419, 46626, 511032, 5761650, 66394596, 778518552, 9258850440, 111417705702, 1354135251538, 16598001854700, 204945037918800, 2546849778687138, 31828936270676172, 399777371427582024, 5043824569861127808, 63892650400004356776
Offset: 0

Views

Author

Seiichi Manyama, Aug 12 2023

Keywords

Crossrefs

Programs

  • Maple
    A364923 := proc(n)
        add( 3^k*(-2)^(n-k)*binomial(n,k)*binomial(3*n+k+1,n)/(3*n+k+1),k=0..n) ;
    end proc:
    seq(A364923(n),n=0..80); # R. J. Mathar, Aug 16 2023
  • PARI
    a(n) = sum(k=0, n, 3^k*(-2)^(n-k)*binomial(n, k)*binomial(3*n+k+1, n)/(3*n+k+1));

Formula

a(n) = Sum_{k=0..n} 3^k * (-2)^(n-k) * binomial(n,k) * binomial(3*n+k+1,n) / (3*n+k+1).
a(n) = (1/n) * Sum_{k=0..n-1} 2^k * binomial(n,k) * binomial(4*n-k,n-1-k) for n > 0.
a(n) = (1/n) * Sum_{k=1..n} 3^(n-k) * binomial(n,k) * binomial(3*n,k-1) for n > 0.
D-finite with recurrence +270*n*(3*n-1)*(3*n+1)*a(n) +(-9463*n^3 -45948*n^2 +88297*n -35478)*a(n-1) +36*(-9017*n^3 +49691*n^2 -90408*n +54354)*a(n-2) +48*(53*n^3 +1724*n^2 -11161*n +16518)*a(n-3) +576*(3*n-10)*(3*n-11) *(n-4)*a(n-4)=0. - R. J. Mathar, Aug 16 2023

A336539 G.f. A(x) satisfies A(x) = 1 + x * A(x)^3 * (1 + 2 * A(x)).

Original entry on oeis.org

1, 3, 33, 498, 8691, 164937, 3305868, 68855862, 1475636055, 32327521077, 720713175441, 16298128820568, 372946723698516, 8619565476744156, 200920644131737992, 4718057697038124750, 111505342455507462207, 2650261296098965752669, 63308992564445668959795
Offset: 0

Views

Author

Seiichi Manyama, Jul 25 2020

Keywords

Crossrefs

Column k=3 of A336574.

Programs

  • Mathematica
    a[n_] := Sum[2^k * Binomial[n, k] * Binomial[3*n + k + 1, n]/(3*n + k + 1), {k, 0, n}];  Array[a, 19, 0] (* Amiram Eldar, Jul 27 2020 *)
  • PARI
    a(n) = my(A=1+x*O(x^n)); for(i=0, n, A=1+x*A^3*(1+2*A)); polcoeff(A, n);
    
  • PARI
    a(n) = sum(k=0, n, 2^k*binomial(n, k)*binomial(3*n+k+1, n)/(3*n+k+1));
    
  • PARI
    a(n) = sum(k=0, n, 2^(n-k)*binomial(3*n+1, k)*binomial(4*n-k, n-k))/(3*n+1); \\ Seiichi Manyama, Jul 26 2020

Formula

a(n) = Sum_{k=0..n} 2^k * binomial(n,k) * binomial(3*n+k+1,n)/(3*n+k+1).
a(n) = (1/(3*n+1)) * Sum_{k=0..n} 2^(n-k) * binomial(3*n+1,k) * binomial(4*n-k,n-k).
a(n) ~ sqrt(168 + 97*sqrt(3)) * (26 + 15*sqrt(3))^(n - 1/2) / (3*sqrt(Pi) * n^(3/2) * 2^(n + 3/2)). - Vaclav Kotesovec, Jul 31 2021
From Seiichi Manyama, Aug 10 2023: (Start)
a(n) = (1/n) * Sum_{k=0..n-1} (-1)^k * 3^(n-k) * binomial(n,k) * binomial(4*n-k,n-1-k) for n > 0.
a(n) = (1/n) * Sum_{k=1..n} 3^k * 2^(n-k) * binomial(n,k) * binomial(3*n,k-1) for n > 0. (End)
a(n) = binomial(1+3*n, n)*hypergeom([-n, 1+3*n], [2+2*n], -2)/(1 + 3*n). - Stefano Spezia, Aug 09 2025

A364792 G.f. satisfies A(x) = 1 + x*A(x)^4 / (1 - x*A(x)^2).

Original entry on oeis.org

1, 1, 5, 33, 250, 2054, 17800, 160183, 1482535, 14022415, 134943095, 1317046306, 13005842030, 129708875695, 1304588594925, 13217663310305, 134775670244250, 1382019265706377, 14242560597119165, 147435736533094415, 1532365596794307010
Offset: 0

Views

Author

Seiichi Manyama, Aug 08 2023

Keywords

Crossrefs

Programs

  • Maple
    A364792 := proc(n)
        if n = 0 then
            1;
        else
            add( binomial(n,k) * binomial(4*n-2*k,n-1-k),k=0..n-1) ;
            %/n ;
        end if ;
    end proc:
    seq(A364792(n),n=0..80); # R. J. Mathar, Aug 10 2023
  • PARI
    a(n) = if(n==0, 1, sum(k=0, n-1, binomial(n, k)*binomial(4*n-2*k, n-1-k))/n);

Formula

a(n) = (1/n) * Sum_{k=0..n-1} binomial(n,k) * binomial(4*n-2*k,n-1-k) for n > 0.
D-finite with recurrence 3*n*(36653*n-48128)*(3*n-1)*(3*n+1)*a(n) +5*(-2160545*n^4 +5139476*n^3 -2463019*n^2 -1385144*n +913296)*a(n-1) +4*(-948403*n^4 +17991137*n^3 -77629283*n^2 +126107767*n -70578450)*a(n-2) +10*(n-3)*(599072*n^3 -5090881*n^2 +13501042*n -11263100)*a(n-3) -50*(6861*n-12886)*(n-3) *(n-4)*(2*n-7)*a(n-4)=0. - R. J. Mathar, Aug 10 2023

A364825 G.f. satisfies A(x) = 1 - x*A(x)^3 * (1 - 3*A(x)).

Original entry on oeis.org

1, 2, 18, 222, 3166, 49098, 804138, 13686198, 239671590, 4290463698, 78160665666, 1444298971662, 27005948771886, 510024567278234, 9714561608833242, 186403770207998310, 3599812021110287862, 69914211761486437026, 1364692279095996581490
Offset: 0

Views

Author

Seiichi Manyama, Aug 09 2023

Keywords

Crossrefs

Programs

  • Maple
    A364825 := proc(n)
        (-1)^n*add( (-3)^k*binomial(n,k) * binomial(3*n+k+1,n)/(3*n+k+1),k=0..n) ;
    end proc:
    seq(A364825(n),n=0..80); # R. J. Mathar, Aug 10 2023
  • PARI
    a(n) = (-1)^n*sum(k=0, n, (-3)^k*binomial(n, k)*binomial(3*n+k+1, n)/(3*n+k+1));

Formula

a(n) = (-1)^n * Sum_{k=0..n} (-3)^k * binomial(n,k) * binomial(3*n+k+1,n) / (3*n+k+1).
a(n) = (1/n) * Sum_{k=0..n-1} 2^(n-k) * binomial(n,k) * binomial(4*n-k,n-1-k) for n > 0.
a(n) = (1/n) * Sum_{k=1..n} 2^k * 3^(n-k) * binomial(n,k) * binomial(3*n,k-1) for n > 0.
D-finite with recurrence +2079*n*(3*n-1)*(3*n+1)*a(n) +(-347173*n^3 +395007*n^2 -41030*n -43092)*a(n-1) +18*(-59207*n^3 +325826*n^2 -590255*n +352406)*a(n-2) +3*(-3299*n^3 +35998*n^2 -125399*n +141144)*a(n-3) +9*(3*n-10)*(3*n-11) *(n-4)*a(n-4)=0. - R. J. Mathar, Aug 10 2023

A378685 G.f. A(x) satisfies A(x) = 1 + x*A(x)^7/(1 - x*A(x)^3).

Original entry on oeis.org

1, 1, 8, 88, 1126, 15716, 232069, 3564835, 56382489, 912031280, 15018257510, 250913307393, 4242722219425, 72470224174650, 1248608968982903, 21673752440979879, 378677335852165297, 6654158090059397480, 117523324766568499072, 2085095374834405245007
Offset: 0

Views

Author

Seiichi Manyama, Dec 04 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=1, s=1, t=7, u=3) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+r));

Formula

G.f. A(x) satisfies A(x) = 1/(1 - x*A(x)^6/(1 - x*A(x)^3)).
If g.f. satisfies A(x) = ( 1 + x*A(x)^(t/r) / (1 - x*A(x)^(u/r))^s )^r, then a(n) = r * Sum_{k=0..n} binomial(t*k+u*(n-k)+r,k) * binomial(n+(s-1)*k-1,n-k)/(t*k+u*(n-k)+r).

A379522 Expansion of (1/x) * Series_Reversion( x / ( (1+x)^3 * (1+2*x)^3 ) ).

Original entry on oeis.org

1, 9, 114, 1683, 27111, 462060, 8192078, 149541975, 2791795695, 53056724409, 1023021616920, 19963667407572, 393536736830724, 7824888965728584, 156750391932619254, 3160558799674447167, 64092227061832430895, 1306327265854324847595, 26746550927141536784370
Offset: 0

Views

Author

Seiichi Manyama, Dec 24 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serreverse(x/((1+x)^3*(1+2*x)^3))/x)
    
  • PARI
    a(n) = sum(k=0, n, 2^k*binomial(3*(n+1), k)*binomial(3*(n+1), n-k))/(n+1);

Formula

a(n) = (1/(n+1)) * Sum_{k=0..n} 2^k * binomial(3*(n+1),k) * binomial(3*(n+1),n-k).
a(n) = (1/(n+1)) * [x^n] ( (1+x) * (1+2*x) )^(3*(n+1)).

A378670 G.f. A(x) satisfies A(x) = 1/( 1 - x*A(x)^(3/2)/(1 - x*A(x)^(3/2)) )^2.

Original entry on oeis.org

1, 2, 11, 78, 627, 5432, 49464, 466726, 4522871, 44747874, 450127999, 4589821576, 47333631828, 492836382192, 5173697858508, 54700317431958, 581946708333055, 6225343630256678, 66921440314606905, 722546760572660030, 7832054418695360555, 85198490262065775840
Offset: 0

Views

Author

Seiichi Manyama, Dec 02 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = 2*sum(k=0, n, 2^k*(-1)^(n-k)*binomial(n, k)*binomial(3*n+k+2, n)/(3*n+k+2));
    
  • PARI
    a(n, r=2, s=1, t=4, u=3) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+r));

Formula

G.f.: exp( 2/3 * Sum_{k>=1} A378612(k) * x^k/k ).
G.f.: B(x)^2 where B(x) is the g.f. of A243659.
a(n) = 2 * Sum_{k=0..n} 2^k * (-1)^(n-k) * binomial(n,k) * binomial(3*n+k+2,n)/(3*n+k+2).
a(n) = 2 * Sum_{k=0..n} binomial(3*n+k+2,k) * binomial(n-1,n-k)/(3*n+k+2).
G.f. A(x) satisfies A(x) = ( 1 + x*A(x)^2/(1 - x*A(x)^(3/2)) )^2.
Showing 1-10 of 11 results. Next