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.

A369299 Expansion of (1/x) * Series_Reversion( x * (1-x) * (1-x^3)^3 ).

Original entry on oeis.org

1, 1, 2, 8, 29, 105, 417, 1719, 7181, 30603, 132736, 582790, 2585352, 11575613, 52237278, 237328704, 1084701387, 4983867447, 23007263941, 106658256768, 496336303014, 2317687534865, 10856677523580, 51001805706435, 240225121539000, 1134240896062656, 5367428039668751
Offset: 0

Views

Author

Seiichi Manyama, Jan 18 2024

Keywords

Crossrefs

Programs

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

Formula

a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(3*n+k+2,k) * binomial(2*n-3*k,n-3*k).
a(n) = (1/(n+1)) * [x^n] 1/( (1-x) * (1-x^3)^3 )^(n+1). - Seiichi Manyama, Feb 14 2024

A369296 Expansion of (1/x) * Series_Reversion( x * (1-x) * (1-x^3)^2 ).

Original entry on oeis.org

1, 1, 2, 7, 24, 84, 315, 1225, 4859, 19646, 80739, 336050, 1413587, 6000777, 25674462, 110598855, 479286932, 2088036939, 9139604421, 40174594432, 177267942918, 784889441217, 3486198469890, 15529021825140, 69355660644738, 310509670642611, 1393296782758244
Offset: 0

Views

Author

Seiichi Manyama, Jan 18 2024

Keywords

Crossrefs

Programs

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

Formula

a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(2*n+k+1,k) * binomial(2*n-3*k,n-3*k).
a(n) = (1/(n+1)) * [x^n] 1/( (1-x) * (1-x^3)^2 )^(n+1). - Seiichi Manyama, Feb 14 2024

A369297 Expansion of (1/x) * Series_Reversion( x * (1-x)^2 * (1-x^3) ).

Original entry on oeis.org

1, 2, 7, 31, 153, 806, 4440, 25266, 147364, 876282, 5292527, 32378125, 200218715, 1249456536, 7858638756, 49766595855, 317051378103, 2030589300596, 13066646029059, 84439101344619, 547746622599561, 3565472378360110, 23282050305073680, 152466688160732190
Offset: 0

Views

Author

Seiichi Manyama, Jan 18 2024

Keywords

Crossrefs

Programs

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

Formula

a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(n+k,k) * binomial(3*n-3*k+1,n-3*k).
a(n) = (1/(n+1)) * [x^n] 1/( (1-x)^2 * (1-x^3) )^(n+1). - Seiichi Manyama, Feb 14 2024

A366041 Expansion of (1/x) * Series_Reversion( x*(1-x)*(1-x^4) ).

Original entry on oeis.org

1, 1, 2, 5, 15, 48, 160, 549, 1930, 6919, 25200, 92976, 346757, 1305140, 4951216, 18912245, 72675114, 280761670, 1089800270, 4248149795, 16623209911, 65273370720, 257115465600, 1015719256200, 4023178881540, 15974388769653, 63570826294760
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2023

Keywords

Crossrefs

Programs

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

Formula

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

A366042 Expansion of (1/x) * Series_Reversion( x*(1-x)*(1-x^5) ).

Original entry on oeis.org

1, 1, 2, 5, 14, 43, 139, 465, 1595, 5577, 19805, 71240, 259037, 950590, 3516110, 13095440, 49068051, 184839543, 699607625, 2659276675, 10147039881, 38853068780, 149240187330, 574913637375, 2220609902199, 8598120578442, 33366877654697, 129758691426484
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2023

Keywords

Crossrefs

Programs

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

Formula

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

A370272 Coefficient of x^n in the expansion of 1/( (1-x) * (1-x^3) )^n.

Original entry on oeis.org

1, 1, 3, 13, 51, 201, 819, 3382, 14067, 58927, 248303, 1051128, 4466787, 19043766, 81418746, 348936288, 1498601459, 6448162221, 27791057997, 119954739879, 518451715551, 2243481128020, 9718784202240, 42143960004750, 182917942802595, 794589638379576
Offset: 0

Views

Author

Seiichi Manyama, Feb 13 2024

Keywords

Crossrefs

Cf. A063030.

Programs

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

Formula

a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,k) * binomial(2*n-3*k-1,n-3*k).
The g.f. exp( Sum_{k>=1} a(k) * x^k/k ) has integer coefficients and equals (1/x) * Series_Reversion( x * (1-x) * (1-x^3) ).
Showing 1-6 of 6 results.