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.

Previous Showing 11-15 of 15 results.

A376320 G.f. satisfies A(x) = (1 + x*A(x)*(1 + x*A(x)))^4.

Original entry on oeis.org

1, 4, 26, 200, 1691, 15180, 142038, 1370076, 13526645, 136024876, 1388394234, 14346699052, 149790104030, 1577765967600, 16745718467070, 178912981116840, 1922688816819276, 20769064846817136, 225384498769815750, 2455985319885345820, 26862562977746930145, 294807644917408047060
Offset: 0

Views

Author

Seiichi Manyama, Sep 20 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=1, t=4) = sum(k=0, n, binomial(t*(n+1), k)*binomial(s*k, n-k))/(n+1);
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serreverse(x/(1+x+x^2)^4)/x)

Formula

If g.f. satisfies A(x) = (1 + x*A(x)*(1 + x*A(x))^s)^t, then a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(t*(n+1),k) * binomial(s*k,n-k).
G.f.: (1/x) * Series_Reversion( x / (1+x+x^2)^4 ).
G.f.: B(x)^4, where B(x) is the g.f. of A365183.

A376328 G.f. satisfies A(x) = (1 + x*A(x)*(1 + x*A(x)))^5.

Original entry on oeis.org

1, 5, 40, 380, 3970, 44051, 509575, 6077435, 74194780, 922644310, 11646083631, 148827827450, 1921724362880, 25034267112600, 328614891689845, 4342322118727300, 57715241768897445, 771087466276360970, 10349495416322497575, 139486475071720234920, 1886980259513934080860, 25613816043115261657425
Offset: 0

Views

Author

Seiichi Manyama, Sep 20 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=1, t=5) = sum(k=0, n, binomial(t*(n+1), k)*binomial(s*k, n-k))/(n+1);
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serreverse(x/(1+x+x^2)^5)/x)

Formula

If g.f. satisfies A(x) = (1 + x*A(x)*(1 + x*A(x))^s)^t, then a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(t*(n+1),k) * binomial(s*k,n-k).
G.f.: (1/x) * Series_Reversion( x / (1+x+x^2)^5 ).
G.f.: B(x)^5, where B(x) is the g.f. of A365189.

A027909 T(2n,n-1), T given by A027907.

Original entry on oeis.org

1, 4, 21, 112, 615, 3432, 19383, 110448, 633726, 3656360, 21191555, 123286440, 719539015, 4210967880, 24702429825, 145210795200, 855172338570, 5044470461352, 29799593861974, 176268499363840, 1043889366927771, 6188748520285584, 36726461258947569, 218146172715259488, 1296812014083995850
Offset: 0

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Author

Keywords

Programs

  • Maple
    seq(add(binomial(j,2*j-3*n-4)*binomial(2*n+2,j),j=0...2*n+2),n=0..25);  # Mark van Hoeij, May 12 2013
  • PARI
    a(n)=sum(j=0,2*n+2,binomial(j, 2*j-3*n-4)*binomial(2*n+2, j)); \\ Joerg Arndt, May 13 2013~

Formula

G.f.: -g*(g^2+g+1)/(3*g^2+g-1) where g = x times the g.f. of A143927. - Mark van Hoeij, Nov 16 2011

Extensions

Corrected offset, more terms, Joerg Arndt, May 13 2013

A027911 a(n) = T(2*n+1,n), with T given by A027907.

Original entry on oeis.org

1, 3, 15, 77, 414, 2277, 12727, 71955, 410346, 2355962, 13599915, 78855339, 458917850, 2679183405, 15683407785, 92022516525, 541050073146, 3186886397310, 18801598011274, 111083331666918, 657153430251396, 3892199032434105, 23077435617920925, 136963282273730613, 813597690808666386
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    seq(add(binomial(j,2*j-2-3*n)*binomial(2*n+1,j),j=0...2*n+1),n=0..20);  # Mark van Hoeij, May 12 2013
  • Mathematica
    Table[GegenbauerC[n, -2 n - 1, -1/2], {n, 0, 100}] (* Emanuele Munarini, Oct 20 2016 *)
  • Maxima
    makelist(ultraspherical(n,-2*n-1,-1/2),n,0,12); /* Emanuele Munarini, Oct 20 2016 */
    
  • PARI
    a(n)=sum(j=0, 2*n+1, binomial(j, 2*j-2-3*n)*binomial(2*n+1, j)); \\ Joerg Arndt, Oct 20 2016

Formula

a(n) = GegenbauerPoly(n,-2*n-1,-1/2). - Emanuele Munarini, Oct 20 2016
G.f.: g/(1-g-3*g^2), where g = x times the g.f. of A143927. - Mark van Hoeij, Nov 16 2011
a(n) = Sum_{k=0..floor(n/2)} binomial(2*n+1,k)*binomial(2*n+1-k,n-2*k). - Emanuele Munarini, Oct 20 2016

Extensions

More terms from Joerg Arndt, Oct 20 2016

A369506 Expansion of (1/x) * Series_Reversion( x / ((1+x)^3+x^2)^2 ).

Original entry on oeis.org

1, 6, 53, 548, 6192, 74074, 922142, 11822082, 155024190, 2069570934, 28033435791, 384329462490, 5322745393480, 74357950874850, 1046564375245893, 14826433687124098, 211251475010201934, 3025331234242178508, 43523061969049245589, 628692982662691174722
Offset: 0

Views

Author

Seiichi Manyama, Jan 25 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^3+x^2)^2)/x)
    
  • PARI
    a(n) = sum(k=0, n\2, binomial(2*n+2, k)*binomial(6*n-3*k+6, n-2*k))/(n+1);

Formula

a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(2*n+2,k) * binomial(6*n-3*k+6,n-2*k).
Previous Showing 11-15 of 15 results.