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 1-5 of 5 results.

A286509 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, 0, 0, 1, -4, 6, -2, -1, 0, 1, -5, 10, -7, -1, 1, 0, 1, -6, 15, -16, 3, 4, -1, 0, 1, -7, 21, -30, 15, 6, -6, 1, 0, 1, -8, 28, -50, 40, 0, -17, 6, 0, 0, 1, -9, 36, -77, 84, -26, -30, 24, -3, -1, 0, 1, -10, 45, -112, 154, -90, -30, 64, -21, -2, 2, 0, 1, -11, 55, -156, 258, -217, 15, 125, -81, 6, 9, -3, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, May 10 2017

Keywords

Examples

			Square array begins:
1,  1,  1,  1,   1,   1,  ...
0, -1, -2, -3,  -4,  -5,  ...
0,  1,  3,  6,  10,  15,  ...
0,  0, -2, -7, -16, -30,  ...
0, -1, -1,  3,  15,  40,  ...
0,  1,  4,  6,   0, -26,  ...
		

Crossrefs

Columns k=0-5 give: A000007, A007325, A055101, A055102, A055103, A078905 (with offset 0).
Rows n=0-2 give: A000012, A001489, A000217.
Main diagonal gives A291651.
Antidiagonal sums give A302015.

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[Product[(1 - x^(5 i - 1)) (1 - x^(5 i - 4))/((1 - x^(5 i - 2)) (1 - x^(5 i - 3))), {i, n}]^k, {x, 0, n}]][j - n], {j, 0, 12},{n, 0, j}] // Flatten

Formula

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

A291653 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, 13, 55, 236, 1035, 4593, 20551, 92578, 419338, 1907951, 8713555, 39921038, 183396671, 844515563, 3896933367, 18014916576, 83415684654, 386807933378, 1796024496430, 8349190182990, 38854827380075, 180997895984903, 843906670596499, 3938005827167461, 18390418912425940
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 28 2017

Keywords

Crossrefs

Main diagonal of A291652.

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1 + ContinuedFractionK[-x^i, 1, {i, 1, n}])^n, {x, 0, n}], {n, 0, 26}]

Formula

a(n) = A291652(n,n).
a(n) ~ c * d^n / sqrt(n), where d = 4.760595370947474723688065553003203505424287110594102605580439495640678... and c = 0.22756527349964754363249384886359862025065238... - Vaclav Kotesovec, Apr 08 2018

A301629 G.f. A(x) satisfies: A(x) = 1/(1 + x*A(x)/(1 + x^2*A(x)^2/(1 + x^3*A(x)^3/(1 + x^4*A(x)^4/(1 + ...))))), a continued fraction.

Original entry on oeis.org

1, -1, 2, -4, 8, -15, 23, -14, -95, 616, -2597, 9280, -29971, 89283, -245617, 614122, -1330205, 2121789, -134318, -18870272, 111955244, -481559262, 1783749762, -5976975892, 18406561660, -52025500982, 132347403714, -285820317372, 421120353772, 271625450178, -5772145145591
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 24 2018

Keywords

Examples

			G.f. A(x) = 1 - x + 2*x^2 - 4*x^3 + 8*x^4 - 15*x^5 + 23*x^6 - 14*x^7 - 95*x^8 + 616*x^9 - 2597*x^10 + ...
log(A(x)) = -x + 3*x^2/2 - 7*x^3/3 + 15*x^4/4 - 26*x^5/5 + 15*x^6/6 + 153*x^7/7 - 1049*x^8/8 + ... + A291651(n)*x^n/n + ...
		

Crossrefs

A291679 Main diagonal of A291678.

Original entry on oeis.org

1, 1, 1, -2, -11, -24, -8, 141, 573, 1087, -174, -8700, -31328, -52740, 36387, 534198, 1742445, 2540583, -3626189, -33115232, -97968686, -118497822, 301668764, 2060526393, 5526622320, 5165256226, -23033840842, -127995025736, -310560935969, -193716799472
Offset: 0

Views

Author

Seiichi Manyama, Aug 29 2017

Keywords

Crossrefs

Formula

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

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 1-5 of 5 results.