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.

A291651 a(n) = [x^n] (1/(1 + x/(1 + x^2/(1 + x^3/(1 + x^4/(1 + x^5/(1 + ...)))))))^n, a continued fraction.

Original entry on oeis.org

1, -1, 3, -7, 15, -26, 15, 153, -1049, 4790, -18522, 64481, -206181, 606384, -1615121, 3715993, -6289929, 550850, 61250694, -382787092, 1726745790, -6691501530, 23413714107, -75179994017, 221304346963, -586004040651, 1318720868416, -2044320913276, -1137686341077, 28530838758784, -165361803129585
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 28 2017

Keywords

Crossrefs

Main diagonal of A286509.
Cf. A291335.

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1 + ContinuedFractionK[x^i, 1, {i, 1, n}])^n, {x, 0, n}], {n, 0, 30}]

Formula

a(n) = A286509(n,n).

A291652 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of k-th power of continued fraction 1/(1 - x/(1 - x^2/(1 - x^3/(1 - x^4/(1 - x^5/(1 - ...)))))).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 3, 2, 0, 1, 4, 6, 6, 3, 0, 1, 5, 10, 13, 11, 5, 0, 1, 6, 15, 24, 27, 20, 9, 0, 1, 7, 21, 40, 55, 54, 38, 15, 0, 1, 8, 28, 62, 100, 120, 109, 70, 26, 0, 1, 9, 36, 91, 168, 236, 258, 216, 129, 45, 0, 1, 10, 45, 128, 266, 426, 540, 544, 423, 238, 78, 0, 1, 11, 55, 174, 402, 721, 1035, 1205, 1127, 824, 437, 135, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 28 2017

Keywords

Examples

			G.f. of column k: A_k(x) = 1 + k*x + k*(k + 1)*x^2/2 +  k*(k^2 + 3*k + 8)*x^3/6 + k*(k^3 + 6*k^2 + 35*k + 30)*x^4/24 + ...
Square array begins:
1,  1,   1,   1,    1,    1,  ...
0,  1,   2,   3,    4,    5,  ...
0,  1,   3,   6,   10,   15,  ...
0,  2,   6,  13,   24,   40,  ...
0,  3,  11,  27,   55,  100,  ...
0,  5,  20,  54,  120,  236,  ...
		

Crossrefs

Columns k=0..1 give A000007, A005169.
Rows n=0..3 give A000012, A001477, A000217, A003600 (with a(0)=0).
Main diagonal gives A291653.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 + ContinuedFractionK[-x^i, 1, {i, 1, n}])^k, {x, 0, n}]][j - n], {j, 0, 12}, {n, 0, j}] // Flatten
    Table[Function[k, SeriesCoefficient[((Sum[(-1)^i x^(i (i + 1))/Product[(1 - x^m), {m, 1, i}], {i, 0, n}])/(Sum[(-1)^i x^(i^2)/Product[(1 - x^m), {m, 1, i}], {i, 0, n}]))^k, {x, 0, n}]][j - n], {j, 0, 12}, {n, 0, j}] // Flatten

Formula

G.f. of column k: (1/(1 - x/(1 - x^2/(1 - x^3/(1 - x^4/(1 - x^5/(1 - ...)))))))^k, a continued fraction.

A291678 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of k-th power of continued fraction 1 + x/(1 + x^2/(1 + x^3/(1 + x^4/(1 + x^5/(1 + ...))))).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 0, 0, 1, 3, 1, -1, 0, 1, 4, 3, -2, 0, 0, 1, 5, 6, -2, -2, 1, 0, 1, 6, 10, 0, -6, 2, 1, 0, 1, 7, 15, 5, -11, 0, 5, -1, 0, 1, 8, 21, 14, -15, -8, 12, 0, -2, 0, 1, 9, 28, 28, -15, -24, 18, 9, -8, 0, 0, 1, 10, 36, 48, -7, -48, 15, 32, -15, -6, 2
Offset: 0

Views

Author

Seiichi Manyama, Aug 29 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,  1,   1, ...
   0,  1,  2,  3,   4, ...
   0,  0,  1,  3,   6, ...
   0, -1, -2, -2,   0, ...
   0,  0, -2, -6, -11, ...
		

Crossrefs

Columns k=0..4 give A000007, A003823, A285442, A285443, A285444.
Rows n=0..1 give A000012, A001477.
Main diagonal gives A291679.
Antidiagonal sums give A302016.
Cf. A286509.

Formula

G.f. of column k: Product_{j>=1} ((1 - x^(5*j-2))*(1 - x^(5*j-3)) / ((1 - x^(5*j-1))*(1 - x^(5*j-4))))^k.

A286932 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of continued fraction 1/(1 + k*x/(1 + k*x^2/(1 + k*x^3/(1 + k*x^4/(1 + k*x^5/(1 + ...)))))).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -2, 1, 0, 1, -3, 4, 0, 0, 1, -4, 9, -4, -1, 0, 1, -5, 16, -18, 0, 1, 0, 1, -6, 25, -48, 27, 8, -1, 0, 1, -7, 36, -100, 128, -27, -24, 1, 0, 1, -8, 49, -180, 375, -320, -27, 48, 0, 0, 1, -9, 64, -294, 864, -1375, 704, 243, -64, -1, 0, 1, -10, 81, -448, 1715, -4104, 4875, -1280, -810, 48, 2, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, May 16 2017

Keywords

Examples

			G.f. of column k: A(x) = 1 - k*x + k^2*x^2 - (k - 1)*k^2*x^3 + (k - 2)*k^3*x^4 - k^3*(k^2 - 3*k + 1)*x^5 + ...
Square array begins:
  1,  1,  1,   1,    1,     1,  ...
  0, -1, -2,  -3,   -4,    -5,  ...
  0,  1,  4,   9,   16,    25,  ...
  0,  0, -4, -18,  -48,  -100,  ...
  0, -1,  0,  27,  128,   375,  ...
  0,  1,  8, -27, -320, -1375,  ...
		

Crossrefs

Columns k=0..1 give: A000007, A007325.
Rows n=0..3 give: A000012, A001489, A000290, A045991 (gives absolute value).
Main diagonal gives A291335.
Cf. A286509.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 + ContinuedFractionK[k x^i, 1, {i, 1, n}]), {x, 0, n}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten

Formula

G.f. of column k: 1/(1 + k*x/(1 + k*x^2/(1 + k*x^3/(1 + k*x^4/(1 + k*x^5/(1 + ...)))))), a continued fraction.
G.f. of column k (for k > 0): (Sum_{j>=0} k^j*x^(j*(j+1))/Product_{i=1..j} (1 - x^i)) / (Sum_{j>=0} k^j*x^(j^2)/Product_{i=1..j} (1 - x^i)).

A302015 Expansion of 1/(1 - x/(1 + x/(1 + x^2/(1 + x^3/(1 + x^4/(1 + x^5/(1 + ...))))))), a continued fraction.

Original entry on oeis.org

1, 1, 0, 0, 1, 0, -1, 0, 1, 0, -1, 1, 1, -2, -1, 2, 0, -2, 2, 3, -3, -3, 4, 0, -7, 3, 9, -5, -7, 10, 4, -17, -1, 21, -7, -21, 21, 19, -36, -13, 47, -5, -56, 36, 64, -69, -54, 104, 15, -147, 41, 177, -115, -168, 221, 116, -344, -15, 442, -159, -481, 422, 443, -736, -280, 1034, -90, -1276, 681
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 30 2018

Keywords

Crossrefs

Antidiagonal sums of A286509.

Programs

  • Mathematica
    nmax = 68; CoefficientList[Series[1/(1 - x/(1 + ContinuedFractionK[x^k, 1, {k, 1, nmax}])), {x, 0, nmax}], x]
    nmax = 68; CoefficientList[Series[1/(1 - x QPochhammer[x, x^5] QPochhammer[x^4, x^5]/(QPochhammer[x^2, x^5] QPochhammer[x^3, x^5])), {x, 0, nmax}], x]

Formula

G.f.: 1/(1 - x*Product_{k>=1} (1 - x^(5*k-1))*(1 - x^(5*k-4))/((1 - x^(5*k-2))*(1 - x^(5*k-3)))).
a(0) = 1; a(n) = Sum_{k=1..n} A007325(k-1)*a(n-k).

A295703 Expansion of R(x*R(x)), where R(x) = 1/(1 + x/(1 + x^2/(1 + x^3/(1 + x^4/(1 + ...))))), a continued fraction (g.f. for A007325).

Original entry on oeis.org

1, -1, 2, -3, 2, 4, -18, 43, -80, 123, -148, 78, 287, -1364, 3858, -8627, 15901, -23076, 20061, 18294, -140623, 420241, -930040, 1655753, -2293975, 1872682, 1835066, -12983537, 37871888, -83222132, 149287250, -212064236, 186932259, 131172644, -1139053896, 3449157957, -7710640256
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 29 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 36; CoefficientList[Series[1/(1 + ContinuedFractionK[(x/(1 + ContinuedFractionK[x^k, 1, {k, 1, nmax}]))^k, 1, {k, 1, nmax}]), {x, 0, nmax}], x]
    g[x_] := g[x] = QPochhammer[x, x^5] QPochhammer[x^4, x^5]/(QPochhammer[x^2, x^5] QPochhammer[x^3, x^5]); a[n_] := a[n] = SeriesCoefficient[g[x g[x]], {x, 0, n}];  Table[a[n], {n, 0, 36}]

Formula

G.f.: 1/(1 + x/(1 + x/(1 + x^2/(1 + x^3/(1 + ...))))/(1 + x^2/(1 + x/(1 + x^2/(1 + x^3/(1 + ...))))^2/(1 + x^3/(1 + x/(1 + x^2/(1 + x^3/(1 + ...))))^3/(1 + ...)))), a continued fraction.
Showing 1-6 of 6 results.