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 1-9 of 9 results.

A108479 Antidiagonal sums of number triangle A086645.

Original entry on oeis.org

1, 1, 2, 7, 17, 44, 117, 305, 798, 2091, 5473, 14328, 37513, 98209, 257114, 673135, 1762289, 4613732, 12078909, 31622993, 82790070, 216747219, 567451585, 1485607536, 3889371025, 10182505537, 26658145586, 69791931223, 182717648081
Offset: 0

Views

Author

Paul Barry, Jun 04 2005

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{2,1,2,-1},{1,1,2,7},30] (* Harvey P. Dale, Jun 01 2021 *)

Formula

G.f.: (1 - x - x^2)/(1 - 2*x - x^2 - 2*x^3 + x^4).
a(n) = 2*(n-1) + a(n-2) + 2*a(n-3) - a(n-4).
a(n) = Sum_{k=0..floor(n/2)} C(2*(n-k), 2*k).
a(n) = Sum_{k=0..floor(n/2)} Sum_{j=0..n-k} C(2*(n-2*k), j) * C(2*k, j).
a(n) = A005252(2*n). - Seiichi Manyama, Aug 11 2024

A376730 Expansion of (1 - x^3 - x^4)/((1 - x^3 - x^4)^2 - 4*x^7).

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 1, 6, 1, 1, 15, 15, 2, 28, 70, 29, 46, 210, 211, 111, 496, 925, 586, 1067, 3005, 3123, 2821, 8100, 13024, 11068, 20385, 44068, 48604, 57325, 129261, 192224, 200585, 358806, 662117, 781433, 1055567, 2050819, 2941702, 3524140, 6067682, 10169037
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=50, x='x+O('x^N)); Vec((1-x^3-x^4)/((1-x^3-x^4)^2-4*x^7))
    
  • PARI
    a(n) = sum(k=0, n\3, binomial(2*k, 2*n-6*k));

Formula

a(n) = 2*a(n-3) + 2*a(n-4) - a(n-6) + 2*a(n-7) - a(n-8).
a(n) = Sum_{k=0..floor(n/3)} binomial(2*k,2*n-6*k).

A376723 Expansion of 1/((1 - x^2 - x^3)^2 - 4*x^5).

Original entry on oeis.org

1, 0, 2, 2, 3, 10, 7, 28, 33, 64, 132, 170, 408, 578, 1119, 2002, 3194, 6310, 10021, 18666, 32353, 55450, 101443, 170672, 308744, 534820, 935936, 1663892, 2872669, 5111652, 8898082, 15641802, 27538647, 48049562, 84813451, 148219128, 260572901, 457451088
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(1/((1-x^2-x^3)^2-4*x^5))
    
  • PARI
    a(n) = sum(k=0, n\2, binomial(2*k+2, 2*n-4*k+1))/2;

Formula

a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) + 2*a(n-5) - a(n-6).
a(n) = (1/2) * Sum_{k=0..floor(n/2)} binomial(2*k+2,2*n-4*k+1).

A376726 Expansion of (1 + x^2 - x^3)/((1 + x^2 - x^3)^2 - 4*x^2).

Original entry on oeis.org

1, 0, 3, 1, 5, 10, 8, 35, 30, 85, 137, 201, 476, 616, 1357, 2172, 3735, 7193, 11213, 21782, 36064, 64095, 115130, 193769, 354737, 604049, 1074008, 1889968, 3273785, 5839608, 10106859, 17880785, 31325077, 54793282, 96710296, 168730043, 297336790, 520856765, 913684857
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec((1+x^2-x^3)/((1+x^2-x^3)^2-4*x^2))
    
  • PARI
    a(n) = sum(k=0, n\2, binomial(2*k+1, 2*n-4*k+1));

Formula

a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) + 2*a(n-5) - a(n-6).
a(n) = Sum_{k=0..floor(n/2)} binomial(2*k+1,2*n-4*k+1).

A376731 Expansion of (1 - x^4 - x^5)/((1 - x^4 - x^5)^2 - 4*x^9).

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 0, 0, 1, 6, 1, 0, 1, 15, 15, 1, 1, 28, 70, 28, 2, 45, 210, 210, 46, 67, 495, 924, 496, 157, 1002, 3003, 3004, 1121, 1911, 8009, 12871, 8161, 4880, 18684, 43760, 43948, 23409, 41820, 126124, 184988, 133285, 113373, 324616, 647112, 657273, 454366
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=60, x='x+O('x^N)); Vec((1-x^4-x^5)/((1-x^4-x^5)^2-4*x^9))
    
  • PARI
    a(n) = sum(k=0, n\4, binomial(2*k, 2*n-8*k));

Formula

a(n) = 2*a(n-4) + 2*a(n-5) - a(n-8) + 2*a(n-9) - a(n-10).
a(n) = Sum_{k=0..floor(n/4)} binomial(2*k,2*n-8*k).

A382300 a(n) = Sum_{k=0..floor(n/2)} (k+1) * binomial(2*k,2*n-4*k).

Original entry on oeis.org

1, 0, 2, 2, 3, 18, 7, 60, 65, 144, 356, 410, 1272, 1722, 3743, 7202, 11482, 25566, 40421, 81610, 147169, 259810, 507267, 867792, 1659112, 2961860, 5362592, 9940420, 17583485, 32564548, 58228386, 105606458, 191831767, 343313042, 625086891, 1119760040, 2023087045
Offset: 0

Views

Author

Seiichi Manyama, Mar 29 2025

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 37); Coefficients(R!( ((1-x^2-x^3)^2 + 4*x^5) / ((1-x^2-x^3)^2 - 4*x^5)^2)); // Vincenzo Librandi, May 11 2025
  • Mathematica
    Table[Sum[(k+1)*Binomial[2*k,2*n-4*k],{k,0,Floor[n/2]}],{n,0,30}] (* Vincenzo Librandi, May 11 2025 *)
  • PARI
    a(n) = sum(k=0, n\2, (k+1)*binomial(2*k, 2*n-4*k));
    
  • PARI
    my(N=1, M=40, x='x+O('x^M), X=1-x^2-x^3, Y=5); Vec(sum(k=0, (N+1)\2, 4^k*binomial(N+1, 2*k)*X^(N+1-2*k)*x^(Y*k))/(X^2-4*x^Y)^(N+1))
    

Formula

G.f.: ((1-x^2-x^3)^2 + 4*x^5) / ((1-x^2-x^3)^2 - 4*x^5)^2.
a(n) = 4*a(n-2) + 4*a(n-3) - 6*a(n-4) - 4*a(n-5) - 2*a(n-6) - 4*a(n-7) - 5*a(n-8) + 8*a(n-9) - 6*a(n-10) + 4*a(n-11) - a(n-12).

A382494 a(n) = Sum_{k=0..floor(n/2)} binomial(k+2,2) * binomial(2*k,2*n-4*k).

Original entry on oeis.org

1, 0, 3, 3, 6, 36, 16, 150, 165, 430, 1071, 1365, 4453, 6258, 14841, 29169, 49941, 115356, 190091, 404811, 750792, 1393956, 2808438, 4988268, 9905746, 18207126, 34231566, 65278964, 119255889, 227648406, 418394087, 782045001, 1457704212, 2681909302
Offset: 0

Views

Author

Seiichi Manyama, Mar 29 2025

Keywords

Crossrefs

Programs

  • Magma
    [&+[Binomial(k+2, 2)*Binomial(2*k, 2*n-4*k): k in [0..n]]: n in [0..41]]; // Vincenzo Librandi, May 11 2025
  • Mathematica
    Table[Sum[Binomial[k+2,2]*Binomial[2*k, 2*n-4*k],{k,0,Floor[n/2]}],{n,0,30}] (* Vincenzo Librandi, May 11 2025 *)
  • PARI
    a(n) = sum(k=0, n\2, binomial(k+2, 2)*binomial(2*k, 2*n-4*k));
    
  • PARI
    my(N=2, M=40, x='x+O('x^M), X=1-x^2-x^3, Y=5); Vec(sum(k=0, (N+1)\2, 4^k*binomial(N+1, 2*k)*X^(N+1-2*k)*x^(Y*k))/(X^2-4*x^Y)^(N+1))
    

Formula

G.f.: (Sum_{k=0..1} 4^k * binomial(3,2*k) * (1-x^2-x^3)^(3-2*k) * x^(5*k)) / ((1-x^2-x^3)^2 - 4*x^5)^3.
a(n) = 6*a(n-2) + 6*a(n-3) - 15*a(n-4) - 18*a(n-5) + 5*a(n-6) + 12*a(n-7) - 3*a(n-8) + 32*a(n-9) + 12*a(n-10) - 6*a(n-11) - 4*a(n-12) + 18*a(n-13) - 33*a(n-14) + 26*a(n-15) - 15*a(n-16) + 6*a(n-17) - a(n-18).

A382495 a(n) = Sum_{k=0..floor(n/2)} binomial(k+3,3) * binomial(2*k,2*n-4*k).

Original entry on oeis.org

1, 0, 4, 4, 10, 60, 30, 300, 335, 1000, 2506, 3500, 11879, 17304, 44220, 88592, 161865, 385704, 660964, 1475100, 2807956, 5459860, 11313094, 20816004, 42774780, 80798128, 157292750, 307887904, 579776799, 1138007940, 2146348214, 4126143900, 7878910238, 14878269368
Offset: 0

Views

Author

Seiichi Manyama, Mar 29 2025

Keywords

Crossrefs

Programs

  • Magma
    [&+[Binomial(k+3, 3)*Binomial(2*k, 2*n-4*k): k in [0..n]]: n in [0..40]]; // Vincenzo Librandi, May 12 2025
  • Mathematica
    Table[Sum[Binomial[k+3,3]*Binomial[2*k, 2*n-4*k],{k,0,Floor[n/2]}],{n,0,33}] (* Vincenzo Librandi, May 12 2025 *)
  • PARI
    a(n) = sum(k=0, n\2, binomial(k+3, 3)*binomial(2*k, 2*n-4*k));
    
  • PARI
    my(N=3, M=40, x='x+O('x^M), X=1-x^2-x^3, Y=5); Vec(sum(k=0, (N+1)\2, 4^k*binomial(N+1, 2*k)*X^(N+1-2*k)*x^(Y*k))/(X^2-4*x^Y)^(N+1))
    

Formula

G.f.: (Sum_{k=0..2} 4^k * binomial(4,2*k) * (1-x^2-x^3)^(4-2*k) * x^(5*k)) / ((1-x^2-x^3)^2 - 4*x^5)^4.
a(n) = 8*a(n-2) + 8*a(n-3) - 28*a(n-4) - 40*a(n-5) + 28*a(n-6) + 72*a(n-7) + 2*a(n-8) + 16*a(n-9) + 20*a(n-10) - 80*a(n-11) - 114*a(n-12) + 56*a(n-13) - 68*a(n-14) + 35*a(n-16) + 40*a(n-17) - 96*a(n-18) + 128*a(n-19) - 110*a(n-20) + 64*a(n-21) - 28*a(n-22) + 8*a(n-23) - a(n-24).

A376787 Expansion of (1 - x^2 + x^3)/((1 - x^2 + x^3)^2 - 4*x^3).

Original entry on oeis.org

1, 0, 1, 3, 1, 10, 6, 21, 36, 43, 127, 139, 340, 540, 881, 1832, 2653, 5427, 8829, 15550, 28642, 46805, 87756, 147575, 262751, 465591, 797864, 1437816, 2471553, 4383696, 7689305, 13402819, 23752217, 41305842, 72916606, 127708213, 223809012, 394045411
Offset: 0

Views

Author

Seiichi Manyama, Oct 04 2024

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1-x^2+x^3)/((1-x^2+x^3)^2-4x^3),{x,0,40}],x] (* or *) LinearRecurrence[{0,2,2,-1,2,-1},{1,0,1,3,1,10},40] (* Harvey P. Dale, Aug 11 2025 *)
  • PARI
    my(N=40, x='x+O('x^N)); Vec((1-x^2+x^3)/((1-x^2+x^3)^2-4*x^3))
    
  • PARI
    a(n) = sum(k=0, n\2, binomial(2*k+1, 2*n-4*k));

Formula

a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) + 2*a(n-5) - a(n-6).
a(n) = Sum_{k=0..floor(n/2)} binomial(2*k+1,2*n-4*k).
Showing 1-9 of 9 results.