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.

A306914 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. 1/((1-x)^k+x^k).

Original entry on oeis.org

1, 1, 0, 1, 2, 0, 1, 3, 2, 0, 1, 4, 6, 0, 0, 1, 5, 10, 9, -4, 0, 1, 6, 15, 20, 9, -8, 0, 1, 7, 21, 35, 34, 0, -8, 0, 1, 8, 28, 56, 70, 48, -27, 0, 0, 1, 9, 36, 84, 126, 125, 48, -81, 16, 0, 1, 10, 45, 120, 210, 252, 200, 0, -162, 32, 0
Offset: 0

Views

Author

Seiichi Manyama, Mar 16 2019

Keywords

Examples

			Square array begins:
   1,  1,    1,    1,   1,    1,    1,    1, ...
   0,  2,    3,    4,   5,    6,    7,    8, ...
   0,  2,    6,   10,  15,   21,   28,   36, ...
   0,  0,    9,   20,  35,   56,   84,  120, ...
   0, -4,    9,   34,  70,  126,  210,  330, ...
   0, -8,    0,   48, 125,  252,  462,  792, ...
   0, -8,  -27,   48, 200,  461,  924, 1716, ...
   0,  0,  -81,    0, 275,  780, 1715, 3432, ...
   0, 16, -162, -164, 275, 1209, 2989, 6434, ...
		

Crossrefs

Columns 1-9 give A000007, A099087, A057083, A099589(n+3), A289389(n+4), A306940, (-1)^n * A049018(n), A306941, A306942.

Programs

  • Mathematica
    A[n_, k_] := SeriesCoefficient[1/((1-x)^k + x^k), {x, 0, n}];
    Table[A[n-k+1, k], {n, 0, 11}, {k, n+1, 1, -1}] // Flatten (* Jean-François Alcover, Mar 20 2019 *)

Formula

A(n,k) = Sum_{j=0..floor(n/k)} (-1)^j * binomial(n+k-1,k*j+k-1).
A(n,2*k) = Sum_{i=0..n} Sum_{j=0..n-i} (-1)^j * binomial(i+k-1,k*j+k-1) * binomial(n-i+k-1,k*j+k-1). - Seiichi Manyama, Apr 07 2019

A289306 a(n) = Sum_{k >= 0}(-1)^k*binomial(n,5*k).

Original entry on oeis.org

1, 1, 1, 1, 1, 0, -5, -20, -55, -125, -250, -450, -725, -1000, -1000, 0, 3625, 13125, 34375, 76875, 153750, 278125, 450000, 621875, 621875, 0, -2250000, -8140625, -21312500, -47656250, -95312500, -172421875, -278984375, -385546875, -385546875, 0, 1394921875
Offset: 0

Views

Author

Vladimir Shevelev, Jul 02 2017

Keywords

Comments

{A289306, A289321, A289387, A289388, A289389} is the difference analog of the trigonometric functions {k_1(x), k_2(x), k_3(x), k_4(x), k_5(x)} of order 5. For the definitions of {k_i(x)} and the difference analog {K_i (n)} see [Erdelyi] and the Shevelev link respectively. - Vladimir Shevelev, Jul 24 2017

References

  • A. Erdelyi, Higher Transcendental Functions, McGraw-Hill, 1955, Vol. 3, Chapter XVIII.

Crossrefs

Programs

  • Mathematica
    Table[Sum[(-1)^k*Binomial[n, 5 k], {k, 0, n}], {n, 0, 36}] (* or *)
    CoefficientList[Series[-((-1 + x)^4/((-1 + x)^5 - x^5)), {x, 0, 36}], x] (* Michael De Vlieger, Jul 04 2017 *)
    LinearRecurrence[{5,-10,10,-5},{1,1,1,1,1},40] (* Harvey P. Dale, Dec 23 2018 *)
  • PARI
    a(n) = sum(k=0, n\5, (-1)^k*binomial(n,5*k)); \\ Michel Marcus, Jul 02 2017

Formula

G.f.: -((-1+x)^4/((-1+x)^5-x^5)). - Peter J. C. Moses, Jul 02 2017
For n>=1, a(n) = (2/5)*(phi+2)^(n/2)*(cos(Pi*n/10) + (phi-1)^n*cos(3 * Pi* n/10)), where phi is the golden ratio. In particular, a(n) = 0 if and only if n==5 (mod 10).
a(n+m) = a(n)*a(m) - K_5(n)*K_2(m) - K_4(n)*K_3(m) - K_3(n)*K_4(m) - K_2(n)*K_5(m), where K_2 is A289321, K_3 is A289387, K_4 is A289388, K_5 is A289389. - Vladimir Shevelev, Jul 24 2017

A307079 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. ((1-x)^(k-2))/((1-x)^k+x^k).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 3, 0, 1, 1, 2, 3, 3, -4, 1, 1, 2, 3, 4, 0, -8, 1, 1, 2, 3, 4, 4, -9, -8, 1, 1, 2, 3, 4, 5, 0, -27, 0, 1, 1, 2, 3, 4, 5, 5, -14, -54, 16, 1, 1, 2, 3, 4, 5, 6, 0, -48, -81, 32, 1, 1, 2, 3, 4, 5, 6, 6, -20, -116, -81, 32, 1
Offset: 0

Views

Author

Seiichi Manyama, Mar 22 2019

Keywords

Examples

			Square array begins:
   1,  1,   1,    1,   1,   1, 1, 1, 1, ...
   1,  2,   2,    2,   2,   2, 2, 2, 2, ...
   1,  2,   3,    3,   3,   3, 3, 3, 3, ...
   1,  0,   3,    4,   4,   4, 4, 4, 4, ...
   1, -4,   0,    4,   5,   5, 5, 5, 5, ...
   1, -8,  -9,    0,   5,   6, 6, 6, 6, ...
   1, -8, -27,  -14,   0,   6, 7, 7, 7, ...
   1,  0, -54,  -48, -20,   0, 7, 8, 8, ...
   1, 16, -81, -116, -75, -27, 0, 8, 9, ...
		

Crossrefs

Columns 1-6 give A000012, A099087, A057682(n+1), A099587(n+1), A289321(n+1), A307089.

Programs

  • Mathematica
    T[n_, k_] := Sum[(-1)^j * Binomial[n+1, k*j+1], {j, 0, Floor[n/k]}]; Table[T[n-k, k], {n, 0, 12}, {k, n, 1, -1}] // Flatten (* Amiram Eldar, May 20 2021 *)

Formula

A(n,k) = Sum_{j=0..floor(n/k)} (-1)^j * binomial(n+1,k*j+1).
A(n,2*k) = Sum_{i=0..n} Sum_{j=0..n-i} (-1)^j * binomial(i,k*j) * binomial(n-i,k*j).

A307394 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. ((1-x)^(k-4))/((1-x)^k+x^k).

Original entry on oeis.org

1, 1, 3, 1, 4, 6, 1, 4, 9, 10, 1, 4, 10, 14, 15, 1, 4, 10, 19, 15, 21, 1, 4, 10, 20, 28, 8, 28, 1, 4, 10, 20, 34, 28, -7, 36, 1, 4, 10, 20, 35, 48, 1, -22, 45, 1, 4, 10, 20, 35, 55, 48, -80, -21, 55, 1, 4, 10, 20, 35, 56, 75, 0, -242, 12, 66, 1, 4, 10, 20, 35, 56, 83, 75, -164, -485, 77, 78
Offset: 0

Views

Author

Seiichi Manyama, Apr 07 2019

Keywords

Examples

			Square array begins:
    1,   1,    1,    1,  1,   1,   1,   1,   1, ...
    3,   4,    4,    4,  4,   4,   4,   4,   4, ...
    6,   9,   10,   10, 10,  10,  10,  10,  10, ...
   10,  14,   19,   20, 20,  20,  20,  20,  20, ...
   15,  15,   28,   34, 35,  35,  35,  35,  35, ...
   21,   8,   28,   48, 55,  56,  56,  56,  56, ...
   28,  -7,    1,   48, 75,  83,  84,  84,  84, ...
   36, -22,  -80,    0, 75, 110, 119, 120, 120, ...
   45, -21, -242, -164,  0, 110, 154, 164, 165, ...
		

Crossrefs

Columns 1-5 give A000217(n+1), A279230, A307395, A099589(n+3), A289388(n+3).

Programs

  • Mathematica
    T[n_, k_] := Sum[(-1)^j * Binomial[n+3, k*j + 3], {j, 0, Floor[n/k]}]; Table[T[n - k, k], {n, 0, 12}, {k, n, 1, -1}] // Flatten (* Amiram Eldar, May 20 2021 *)

Formula

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

A307040 a(n) = Sum_{k=0..floor(n/6)} (-1)^k*binomial(n,6*k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 0, -6, -27, -83, -209, -461, -922, -1702, -2911, -4549, -6187, -6187, 0, 23238, 87021, 238337, 564719, 1217483, 2434966, 4542526, 7865521, 12403951, 16942381, 16942381, 0, -63239286, -236031147, -644886923, -1525870529, -3287837741, -6575675482
Offset: 0

Views

Author

Seiichi Manyama, Mar 21 2019

Keywords

Crossrefs

Column 6 of A307039.
Cf. A306847.

Programs

  • Mathematica
    a[n_] := Sum[(-1)^k * Binomial[n,6*k], {k,0,Floor[n/6]}]; Array[a, 37, 0] (* Amiram Eldar, May 25 2021 *)
  • PARI
    {a(n) = sum(k=0, n\6, (-1)^k*binomial(n, 6*k))}
    
  • PARI
    N=66; x='x+O('x^N); Vec((1-x)^5/((1-x)^6+x^6))

Formula

G.f.: (1 - x)^5/((1 - x)^6 + x^6).
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - 2*a(n-6) for n > 5.

A307041 a(n) = Sum_{k=0..floor(n/7)} (-1)^k*binomial(n,7*k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 0, -7, -35, -119, -329, -791, -1715, -3430, -6419, -11319, -18767, -28763, -38759, -38759, 0, 149205, 571781, 1613129, 3964051, 8934121, 18874261, 37748522, 71705865, 129080161, 218205281, 339081225, 459957169, 459957169, 0, -1749692735
Offset: 0

Views

Author

Seiichi Manyama, Mar 21 2019

Keywords

Crossrefs

Column 7 of A307039.
Cf. A306852.

Programs

  • Mathematica
    a[n_] := Sum[(-1)^k * Binomial[n,7*k], {k,0,Floor[n/7]}]; Array[a, 37, 0] (* Amiram Eldar, May 25 2021 *)
  • PARI
    {a(n) = sum(k=0, n\7, (-1)^k*binomial(n, 7*k))}
    
  • PARI
    N=66; x='x+O('x^N); Vec((1-x)^6/((1-x)^7+x^7))

Formula

G.f.: (1 - x)^6/((1 - x)^7 + x^7).
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) for n > 6.

A307044 a(n) = Sum_{k=0..floor(n/8)} (-1)^k*binomial(n,8*k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 0, -8, -44, -164, -494, -1286, -3002, -6434, -12868, -24292, -43604, -74612, -121124, -183140, -245156, -245156, 0, 961376, 3749136, 10814896, 27293176, 63453016, 138975976, 290021896, 580043792, 1114351888, 2054677648, 3619173776
Offset: 0

Views

Author

Seiichi Manyama, Mar 21 2019

Keywords

Crossrefs

Column 8 of A307039.
Cf. A306859.

Programs

  • Mathematica
    a[n_] := Sum[(-1)^k * Binomial[n,8*k], {k,0,Floor[n/8]}]; Array[a, 36, 0] (* Amiram Eldar, May 25 2021 *)
  • PARI
    {a(n) = sum(k=0, n\8, (-1)^k*binomial(n, 8*k))}
    
  • PARI
    N=66; x='x+O('x^N); Vec((1-x)^7/((1-x)^8+x^8))

Formula

G.f.: (1 - x)^7/((1 - x)^8 + x^8).
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - 2*a(n-8) for n > 7.

A307045 a(n) = Sum_{k=0..floor(n/9)} (-1)^k*binomial(n,9*k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 0, -9, -54, -219, -714, -2001, -5004, -11439, -24309, -48618, -92358, -167769, -292599, -490104, -783540, -1172907, -1562274, -1562274, 0, 6216183, 24581880, 72182016, 186061536, 443185425, 997483653, 2146130559, 4443424371, 8886848742
Offset: 0

Views

Author

Seiichi Manyama, Mar 21 2019

Keywords

Crossrefs

Column 9 of A307039.
Cf. A306860.

Programs

  • Mathematica
    a[n_] := Sum[(-1)^k * Binomial[n,9*k], {k,0,Floor[n/9]}]; Array[a, 37, 0] (* Amiram Eldar, May 25 2021 *)
  • PARI
    {a(n) = sum(k=0, n\9, (-1)^k*binomial(n, 9*k))}
    
  • PARI
    N=66; x='x+O('x^N); Vec((1-x)^8/((1-x)^9+x^9))

Formula

G.f.: (1 - x)^8/((1 - x)^9 + x^9).
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) for n > 8.

A307668 A(n,k) = Sum_{j=0..floor(n/k)} (-1)^j*binomial(2*n,k*j+n), square array A(n,k) read by antidiagonals, for n >= 0, k >= 1.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 2, 5, 10, 1, 2, 6, 14, 35, 1, 2, 6, 19, 43, 126, 1, 2, 6, 20, 62, 142, 462, 1, 2, 6, 20, 69, 207, 494, 1716, 1, 2, 6, 20, 70, 242, 705, 1780, 6435, 1, 2, 6, 20, 70, 251, 858, 2445, 6563, 24310, 1, 2, 6, 20, 70, 252, 912, 3068, 8622, 24566, 92378
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2019

Keywords

Examples

			Square array begins:
      1,    1,    1,     1,     1,     1,     1, ...
      1,    2,    2,     2,     2,     2,     2, ...
      3,    5,    6,     6,     6,     6,     6, ...
     10,   14,   19,    20,    20,    20,    20, ...
     35,   43,   62,    69,    70,    70,    70, ...
    126,  142,  207,   242,   251,   252,   252, ...
    462,  494,  705,   858,   912,   923,   924, ...
   1716, 1780, 2445,  3068,  3341,  3418,  3431, ...
   6435, 6563, 8622, 11051, 12310, 12750, 12854, ...
		

Crossrefs

Columns 1-2 give A088218, A005317.

Programs

  • Mathematica
    T[n_, k_] := Sum[(-1)^j*Binomial[2*n, k*j + n], {j, 0, Floor[n/k]}]; Table[T[n - k, k], {n, 0, 11}, {k, n, 1, -1}] // Flatten (* Amiram Eldar, May 13 2021*)
Showing 1-9 of 9 results.