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.

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A291332 a(n) = [x^n] 1/(1 - x/(1 - 3^n*x/(1 - 5^n*x/(1 - 7^n*x/(1 - 9^n*x/(1 - ...)))))), a continued fraction.

Original entry on oeis.org

1, 1, 10, 4159, 162045118, 1063421637466546, 1858323116289048481112500, 1253322341309506161980784960477550459, 445827827888374514639499681047571455105640696771958, 109534636154930845670316103395158313783593902542091687316468724140446
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 22 2017

Keywords

Crossrefs

Main diagonal of A291261.
Cf. A291547.

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1 + ContinuedFractionK[-(2 i - 1)^n x, 1, {i, 1, n}]), {x, 0, n}], {n, 0, 9}]

Formula

a(n) = A291261(n,n).
a(n) ~ c * ((2*n-1)!!)^n ~ c * 2^(n^2 + n/2) * n^(n^2) / exp(n^2 + 1/24), where c = 1/QPochhammer(exp(-1)) = 1.9824409074128737036856824655613120156828827... - Vaclav Kotesovec, Aug 26 2017, updated Jul 21 2018

A291260 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of continued fraction 1/(1 - 2^k*x/(1 - 4^k*x/(1 - 6^k*x/(1 - 8^k*x/(1 - 10^k*x/(1 - ...)))))).

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 4, 12, 5, 1, 8, 80, 120, 14, 1, 16, 576, 3904, 1680, 42, 1, 32, 4352, 152064, 354560, 30240, 132, 1, 64, 33792, 6492160, 99422208, 51733504, 665280, 429, 1, 128, 266240, 290488320, 31832735744, 130292416512, 11070525440, 17297280, 1430
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 21 2017

Keywords

Examples

			Square array begins:
:  1,     1,        1,            1,               1, ...
:  1,     2,        4,            8,              16, ...
:  2,    12,       80,          576,            4352, ...
:  5,   120,     3904,       152064,         6492160, ...
: 14,  1680,   354560,     99422208,     31832735744, ...
: 42, 30240, 51733504, 130292416512, 390365719822336, ...
		

Crossrefs

Columns k=0-2 give A000108, A001813, A002436.
Main diagonal gives A291331.
Cf. A000079 (row 1), A063481 (row 2), A290569, A291261.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 + ContinuedFractionK[-(2 i)^k x, 1, {i, 1, n}]), {x, 0, n}]][j - n], {j, 0, 8}, {n, 0, j}] // Flatten

Formula

G.f. of column k: 1/(1 - 2^k*x/(1 - 4^k*x/(1 - 6^k*x/(1 - 8^k*x/(1 - 10^k*x/(1 - ...)))))), a continued fraction.
Showing 1-2 of 2 results.