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 1-2 of 2 results.

A040042 Continued fraction for sqrt(50) = 5*sqrt(2).

Original entry on oeis.org

7, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14
Offset: 0

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Keywords

Examples

			7.07106781186547524400844... = 7 + 1/(14 + 1/(14 + 1/(14 + 1/(14 + ...)))). - _Harry J. Smith_, Jun 01 2009
		

References

  • James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 276.

Crossrefs

Cf. A010503 (decimal expansion), A041084/A041085 (convergents), A248275 (Egyptian fraction).
Cf. A040000.

Programs

  • Maple
    Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):
  • Mathematica
    ContinuedFraction[Sqrt[50],300] (* Vladimir Joseph Stephan Orlovsky, Mar 07 2011 *)
  • PARI
    { allocatemem(932245000); default(realprecision, 47000); x=contfrac(sqrt(50)); for (n=0, 20000, write("b040042.txt", n, " ", x[n+1])); } \\ Harry J. Smith, Jun 01 2009

Formula

From Elmo R. Oliveira, Feb 07 2024: (Start)
a(n) = 14 = A010853(n) for n >= 1.
G.f.: 7*(1+x)/(1-x).
E.g.f.: 14*exp(x) - 7.
a(n) = 7*A040000(n). (End)

A023012 Number of partitions of n into parts of 14 kinds.

Original entry on oeis.org

1, 14, 119, 770, 4165, 19754, 84602, 333608, 1228080, 4263770, 14071827, 44420796, 134793918, 394805110, 1119974875, 3086034350, 8280022023, 21678277754, 55486209625, 139065013640, 341779759755, 824753397814, 1956347387428
Offset: 0

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Author

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Comments

a(n) is Euler transform of A010853. - Alois P. Heinz, Oct 17 2008

Crossrefs

14th column of A144064. - Alois P. Heinz, Oct 17 2008

Programs

  • Maple
    with(numtheory): a:= proc(n) option remember; `if`(n=0, 1, add(add(d*14, d=divisors(j)) *a(n-j), j=1..n)/n) end: seq(a(n), n=0..40); # Alois P. Heinz, Oct 17 2008
  • Mathematica
    CoefficientList[Series[1/QPochhammer[x]^14, {x, 0, 30}], x] (* Indranil Ghosh, Mar 27 2017 *)
  • PARI
    Vec(1/eta(x)^14 + O(x^30)) \\ Indranil Ghosh, Mar 27 2017

Formula

a(0) = 1, a(n) = (14/n)*Sum_{k=1..n} A000203(k)*a(n-k) for n > 0. - Seiichi Manyama, Mar 27 2017
a(n) ~ m^((m+1)/4) * exp(Pi*sqrt(2*m*n/3)) / (2^((3*m+5)/4) * 3^((m+1)/4) * n^((m+3)/4)) * (1 - ((9+Pi^2)*m^2+36*m+27) / (24*Pi*sqrt(6*m*n))), set m = 14. - Vaclav Kotesovec, Jun 28 2025
Showing 1-2 of 2 results.