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 10 results.

A364336 G.f. satisfies A(x) = (1 + x) * (1 + x*A(x)^3).

Original entry on oeis.org

1, 2, 7, 39, 242, 1634, 11631, 85957, 653245, 5072862, 40077807, 321106623, 2602911282, 21308131235, 175909559897, 1462846379247, 12242600576066, 103035285071630, 871490142773640, 7404121610615520, 63157400073057627, 540689217572662413, 4644083121177225292
Offset: 0

Views

Author

Seiichi Manyama, Jul 19 2023

Keywords

Crossrefs

Programs

  • Maple
    A364336 := proc(n)
        add( binomial(3*k+1,k) * binomial(3*k+1,n-k)/(3*k+1),k=0..n) ;
    end proc:
    seq(A364336(n),n=0..80); # R. J. Mathar, Jul 25 2023
  • Mathematica
    nmax = 80; A[_] = 1;
    Do[A[x_] = (1 + x)*(1 + x*A[x]^3) + O[x]^(nmax+1) // Normal, {nmax+1}];
    CoefficientList[A[x], x] (* Jean-François Alcover, Mar 03 2024 *)
  • PARI
    a(n) = sum(k=0, n, binomial(3*k+1, k)*binomial(3*k+1, n-k)/(3*k+1));

Formula

a(n) = Sum_{k=0..n} binomial(3*k+1,k) * binomial(3*k+1,n-k) / (3*k+1).
D-finite with recurrence -2*n*(2*n+1)*a(n) +(3*n^2+23*n-14)*a(n-1) +(207*n^2 -635*n +494)*a(n-2) +2*(397*n^2 -2031*n +2600)*a(n-3) +6*(75*n-244) *(3*n-11)*a(n-4) +9*(45*n-179) *(3*n-14)*a(n-5) +63*(3*n-14) *(3*n-17)*a(n-6) +12*(3*n-16) *(3*n-20)*a(n-7)=0. - R. J. Mathar, Jul 25 2023
From Peter Bala, Sep 10 2024: (Start)
x/series_reversion(x*A(x)) = 1 + 2*x + 3*x^2 + 13*x^3 + 32*x^4 + 147*x^5 + ..., the g.f. of A216359.
(1/x) * series_reversion(x/A(x)) = 1 + 2*x + 11*x^2 + 89*x^3 + 836*x^4 + 8551*x^5 + ..., the g.f. of A215623. (End)

A364338 G.f. satisfies A(x) = (1 + x) * (1 + x*A(x)^5).

Original entry on oeis.org

1, 2, 11, 105, 1140, 13555, 170637, 2235472, 30161255, 416248640, 5848462880, 83378361111, 1203100853951, 17537182300140, 257858115407535, 3819894878557990, 56958234329850060, 854192593184162160, 12875579347191388830, 194963091634569681550, 2964229359714424159370, 45234864131654311730160
Offset: 0

Views

Author

Seiichi Manyama, Jul 19 2023

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 22; A[] = 0; Do[A[x] = (1+x)(1+x*A[x]^5) + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* Stefano Spezia, Mar 24 2025 *)
  • PARI
    a(n) = sum(k=0, n, binomial(5*k+1, k)*binomial(5*k+1, n-k)/(5*k+1));

Formula

a(n) = Sum_{k=0..n} binomial(5*k+1,k) * binomial(5*k+1,n-k) / (5*k+1).

A364339 G.f. satisfies A(x) = (1 + x) * (1 + x*A(x)^6).

Original entry on oeis.org

1, 2, 13, 150, 1978, 28603, 438273, 6992052, 114915180, 1932233883, 33081722359, 574755965137, 10107627041697, 179576579730534, 3218352405778284, 58114340679967608, 1056284029850962674, 19310039426151335622, 354818596435147647654, 6549556302551204621664, 121394125733645986376838
Offset: 0

Views

Author

Seiichi Manyama, Jul 19 2023

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 21; A[] = 0; Do[A[x] = (1+x)(1+x*A[x]^6) + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* Stefano Spezia, Mar 24 2025 *)
  • PARI
    a(n) = sum(k=0, n, binomial(6*k+1, k)*binomial(6*k+1, n-k)/(6*k+1));

Formula

a(n) = Sum_{k=0..n} binomial(6*k+1,k) * binomial(6*k+1,n-k) / (6*k+1).

A366326 G.f. satisfies A(x) = (1 + x) * (1 + x/A(x)^2).

Original entry on oeis.org

1, 2, -3, 14, -78, 479, -3131, 21372, -150588, 1087057, -7998295, 59763129, -452257495, 3459109408, -26697940390, 207672518808, -1626400971710, 12813379464399, -101482102525511, 807524595076284, -6452856224076654, 51760509258982478, -416620859045829372
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2023

Keywords

Crossrefs

Programs

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

Formula

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

A366325 G.f. satisfies A(x) = (1 + x) * (1 + x/A(x)).

Original entry on oeis.org

1, 2, -1, 3, -10, 36, -137, 543, -2219, 9285, -39587, 171369, -751236, 3328218, -14878455, 67030785, -304036170, 1387247580, -6363044315, 29323149825, -135700543190, 630375241380, -2938391049395, 13739779184085, -64430797069375, 302934667061301, -1427763630578197
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2023

Keywords

Crossrefs

Programs

  • Maple
    a := proc(n) option remember; if n = 1 then 2 elif n = 2 then -1 else (-3*(2*n - 3)*a(n-1) - 5*(n - 3)*a(n-2))/n fi; end:
    seq(a(n), n = 1..30); # Peter Bala, Sep 10 2024
  • PARI
    a(n) = (-1)^(n-1)*sum(k=0, n, binomial(2*k-1, k)*binomial(n-2, n-k)/(2*k-1));

Formula

G.f.: A(x) = -2*x*(1+x) / (1+x-sqrt((1+x)*(1+5*x))).
a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(2*k-1,k) * binomial(n-2,n-k)/(2*k-1).
a(n) ~ -(-1)^n * 5^(n - 1/2) / (2 * sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Oct 07 2023
From Peter Bala, Sep 10 2024: (Start)
a(n) = 1/(1 - n) * Sum_{k = 0..n} binomial(-n+k, k)*binomial(-n+k+1, n-k) for n not equal to 1. Cf. A007863.
a(n) = Sum_{k = 0..n-2} binomial(-n+k+1, k)*binomial(-n+k+1, n-k)/(-n+k+1) for n >= 2.
P-recursive: n*a(n) = - 3*(2*n - 3)*a(n-1) - 5*(n - 3)*a(n-2) with a(1) = 2 and a(2) = -1. (End)

A366327 G.f. satisfies A(x) = (1 + x) * (1 + x/A(x)^3).

Original entry on oeis.org

1, 2, -5, 33, -260, 2263, -20979, 203124, -2030121, 20786694, -216928144, 2298911699, -24673591005, 267644087524, -2929602893537, 32317666058508, -358931896710948, 4010200327457883, -45040693394259858, 508253687784232108, -5759468659295939684
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2023

Keywords

Crossrefs

Programs

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

Formula

a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(4*k-1,k) * binomial(n+2*k-2,n-k)/(4*k-1).

A366328 G.f. satisfies A(x) = (1 + x) * (1 + x/A(x)^4).

Original entry on oeis.org

1, 2, -7, 60, -612, 6898, -82806, 1038076, -13431940, 178040315, -2405137161, 32992706368, -458336721104, 6435090557964, -91167680664004, 1301665779507128, -18710805300530504, 270559054510943509, -3932893180646204203, 57437414168562779574, -842365843304975785062
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = (-1)^(n-1)*sum(k=0, n, binomial(5*k-1, k)*binomial(n+3*k-2, n-k)/(5*k-1));

Formula

a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(5*k-1,k) * binomial(n+3*k-2,n-k)/(5*k-1).

A364373 G.f. satisfies A(x) = (1 + x) * (1 - x*A(x)^4).

Original entry on oeis.org

1, 0, -1, 4, -12, 26, -14, -236, 1604, -6577, 17827, -14064, -186496, 1437856, -6416576, 18733256, -17358808, -201270728, 1652571996, -7692333934, 23375782030, -23913813710, -250917362258, 2147925544190, -10270145045142, 32053993413694, -35259817590134
Offset: 0

Views

Author

Seiichi Manyama, Jul 20 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, (-1)^k*binomial(4*k+1, k)*binomial(4*k+1, n-k)/(4*k+1));

Formula

a(n) = Sum_{k=0..n} (-1)^k * binomial(4*k+1,k) * binomial(4*k+1,n-k) / (4*k+1).

A379039 G.f. A(x) satisfies A(x) = ( (1 + x) * (1 + x*A(x)^2) )^2.

Original entry on oeis.org

1, 4, 22, 172, 1513, 14356, 143228, 1480956, 15728516, 170558634, 1880568650, 21019304814, 237615558790, 2712066792304, 31210387143556, 361738488066632, 4218907281330372, 49476183230651216, 583066018329260673, 6901459436855306662, 82011678696864842013
Offset: 0

Views

Author

Seiichi Manyama, Dec 14 2024

Keywords

Crossrefs

Programs

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

Formula

G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A364337.
a(n) = Sum_{k=0..n} binomial(4*k+2,k) * binomial(4*k+2,n-k)/(2*k+1).

A379038 G.f. A(x) satisfies A(x) = ( (1 + x) * (1 + x*A(x)^(4/3)) )^3.

Original entry on oeis.org

1, 6, 39, 320, 2907, 28152, 284907, 2977116, 31875708, 347884085, 3855802689, 43283239650, 491083601338, 5622489637407, 64877058557079, 753705528179424, 8808460811302728, 103487549564845200, 1221565052783161763, 14480208437556590346, 172299129911222223324
Offset: 0

Views

Author

Seiichi Manyama, Dec 14 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = 3*sum(k=0, n, binomial(4*k+3, k)*binomial(4*k+3, n-k)/(4*k+3));

Formula

G.f.: A(x) = B(x)^3 where B(x) is the g.f. of A364337.
a(n) = 3 * Sum_{k=0..n} binomial(4*k+3,k) * binomial(4*k+3,n-k)/(4*k+3).
Showing 1-10 of 10 results.