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 1-6 of 6 results.

A364740 G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x)^5).

Original entry on oeis.org

1, 1, 3, 15, 91, 607, 4298, 31720, 241321, 1879097, 14903013, 119965086, 977623639, 8049579047, 66864689674, 559650696185, 4715304229460, 39960204165865, 340395043021399, 2912963919210012, 25031055321749916, 215894227588453950, 1868403327770467149
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(2*n+3*k, n-1-k))/n);

Formula

a(n) = (1/n) * Sum_{k=0..n-1} binomial(n,k) * binomial(2*n+3*k,n-1-k) for n > 0.

A364764 G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 + x*A(x)^4).

Original entry on oeis.org

1, 1, 1, -2, -14, -27, 70, 625, 1457, -3541, -37403, -98547, 207098, 2564079, 7448923, -12940485, -190014459, -600991549, 827159379, 14802832468, 50584687754, -52159768068, -1193457862093, -4384199208207, 3090291576246, 98618925147291, 388126462227091
Offset: 0

Views

Author

Seiichi Manyama, Aug 05 2023

Keywords

Crossrefs

Programs

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

Formula

a(n) = (1/n) * Sum_{k=0..n-1} (-1)^k * binomial(n,k) * binomial(2*n+2*k,n-1-k) for n > 0.

A365247 G.f. satisfies A(x) = 1 + x*A(x)^2/(1 - x^3*A(x)^4).

Original entry on oeis.org

1, 1, 2, 5, 15, 50, 177, 650, 2449, 9412, 36761, 145518, 582556, 2354557, 9594898, 39378259, 162619316, 675258452, 2817643240, 11808576745, 49683880754, 209786559004, 888676860191, 3775654643360, 16084818268474, 68694452578325, 294053067958011
Offset: 0

Views

Author

Seiichi Manyama, Aug 28 2023

Keywords

Crossrefs

Programs

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

Formula

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

A364723 G.f. satisfies A(x) = 1 + x*A(x) / (1 - x*A(x)^4).

Original entry on oeis.org

1, 1, 2, 8, 38, 196, 1073, 6120, 35968, 216304, 1324676, 8232981, 51796538, 329229344, 2111031444, 13638557196, 88695018723, 580153216512, 3814285704000, 25192499164320, 167075960048996, 1112162062296061, 7428213584196010, 49766086788057256
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(n+3*k, n-1-k))/n);

Formula

a(n) = (1/n) * Sum_{k=0..n-1} binomial(n,k) * binomial(n+3*k,n-1-k) for n > 0.

A365246 G.f. satisfies A(x) = 1 + x*A(x)^2/(1 - x^2*A(x)^4).

Original entry on oeis.org

1, 1, 2, 6, 22, 88, 370, 1613, 7230, 33117, 154330, 729369, 3487470, 16840346, 82007012, 402269702, 1985867630, 9858739759, 49187798158, 246506563980, 1240337033398, 6263601365616, 31734939452116, 161270637750264, 821802841072422, 4198348868249768
Offset: 0

Views

Author

Seiichi Manyama, Aug 28 2023

Keywords

Crossrefs

Programs

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

Formula

a(n) = (1/(2*n+1)) * Sum_{k=0..floor(n/2)} binomial(n-k-1,k) * binomial(2*n+1,n-2*k).

A378828 G.f. A(x) satisfies A(x) = ( 1 + x*A(x)^(2/3)/(1 - x*A(x)^(4/3)) )^3.

Original entry on oeis.org

1, 3, 12, 61, 354, 2220, 14649, 100218, 704373, 5055383, 36895221, 272975652, 2042782905, 15434838759, 117588475377, 902259691317, 6966487019220, 54086849181609, 421986564474946, 3306818224272945, 26015737668878523, 205405810986995869, 1627042895593132485
Offset: 0

Views

Author

Seiichi Manyama, Dec 09 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=3, s=1, t=2, u=4) = 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)^(1/3)/(1 - x*A(x)^(4/3)) )^3.
G.f. A(x) satisfies A(x) = 1 + x * A(x)^(2/3) * (1 + A(x)^(1/3) + A(x)^(5/3)).
G.f.: A(x) = B(x)^3 where B(x) is the g.f. of A364739.
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).
Showing 1-6 of 6 results.