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 1-10 of 16 results. Next

A011350 Decimal expansion of 6th root of 15.

Original entry on oeis.org

1, 5, 7, 0, 4, 1, 7, 8, 0, 2, 4, 7, 5, 0, 1, 9, 7, 3, 5, 3, 1, 0, 5, 2, 9, 6, 6, 7, 0, 0, 2, 6, 2, 3, 3, 4, 9, 4, 5, 8, 3, 7, 7, 7, 7, 6, 6, 5, 8, 1, 3, 5, 3, 3, 7, 8, 9, 6, 2, 8, 9, 9, 3, 8, 4, 0, 0, 7, 4, 6, 5, 8, 5, 2, 9, 2, 6, 0, 5, 4, 2, 2, 2, 1, 3, 4, 3, 4, 6, 9, 0, 4, 8, 9, 0, 6, 6, 2, 2
Offset: 1

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Author

Keywords

Comments

The 6th root r(6) of the expected value E(x^6) for a normal distribution with zero mean and standard deviation 1. See A289090 for more details. - Stanislav Sykora, Jul 26 2017

Crossrefs

Programs

  • Mathematica
    RealDigits[Power[15, (6)^-1],10,120][[1]]  (* Harvey P. Dale, Apr 09 2011 *)
  • PARI
    sqrtn(15, 6) \\ Michel Marcus, Jul 27 2017

A289090 Decimal expansion of (E(|x|^3))^(1/3), with x being a normally distributed random variable.

Original entry on oeis.org

1, 1, 6, 8, 5, 7, 5, 2, 5, 4, 9, 6, 2, 4, 6, 5, 5, 4, 8, 6, 7, 0, 4, 7, 6, 0, 1, 1, 0, 9, 7, 6, 8, 5, 2, 7, 1, 0, 6, 0, 5, 2, 4, 0, 4, 8, 1, 6, 7, 9, 0, 7, 9, 7, 2, 3, 8, 3, 5, 1, 6, 2, 8, 7, 4, 2, 3, 4, 1, 5, 2, 9, 3, 8, 8, 8, 7, 8, 5, 4, 6, 5, 2, 7, 8, 7, 1, 4, 2, 3, 4, 2, 8, 3, 8, 3, 4, 9, 3, 9, 6, 7, 3, 1, 3
Offset: 1

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Author

Stanislav Sykora, Jul 26 2017

Keywords

Comments

The p-th root r(p) of the expected value E(|x|^p) for various distributions appears, for example, in chemical physics, where some interactions depend on high powers of interatomic distances.
When x is distributed normally with zero mean and standard deviation 1, r(p) evaluates to r(p) = ((p-1)!!*w(p))^(1/p), where w(p) = 1 for even p and sqrt(2/Pi) for odd p. Note that, by definition, r(2) = 1 and r(1) = w(1) = A076668.
The present constant is a = r(3).

Examples

			1.16857525496246554867047601109768527106052404816790797238351628742...
		

Crossrefs

Cf. A060294, A076668 (p=1), A011002 (p=4), A289091 (p=5), A011350 (p=6).

Programs

  • Mathematica
    ExpectedValue[Abs[#]^3&, NormalDistribution[0, 1]]^(1/3) // RealDigits[#, 10, 105]& // First (* Jean-François Alcover, Jul 28 2017 *)
  • PARI
    \\ General code, for any p > 0:
    r(p) = (sqrt(2/Pi)^(p%2)*prod(k=0,(p-2)\2,p-1-2*k))^(1/p);
    a = r(3) \\ Present instance

Formula

Equals (2!!*sqrt(2/Pi))^(1/3) = (2*A076668)^(1/3).

A289091 Decimal expansion of (E(|x|^5))^(1/5), with x being a normally distributed random variable.

Original entry on oeis.org

1, 4, 4, 8, 7, 9, 1, 9, 0, 1, 5, 4, 9, 3, 0, 5, 2, 8, 5, 2, 5, 3, 5, 4, 6, 5, 9, 8, 8, 1, 2, 8, 1, 0, 5, 8, 8, 2, 1, 3, 4, 0, 1, 0, 3, 9, 3, 5, 1, 9, 6, 7, 8, 0, 7, 2, 9, 5, 0, 3, 0, 5, 8, 0, 1, 5, 5, 4, 3, 6, 2, 8, 4, 7, 7, 4, 2, 7, 2, 8, 1, 2, 0, 5, 4, 2, 7, 4, 0, 2, 8, 1, 2, 4, 3, 6, 3, 3, 8, 6, 9, 7, 4, 9, 6
Offset: 1

Views

Author

Stanislav Sykora, Jul 26 2017

Keywords

Comments

The 5th root r(5) of the expected value E(|x|^5) for a normal distribution with zero mean and standard deviation 1. See A289090 for more details.

Examples

			1.44879190154930528525354659881281058821340103935196780729503058015...
		

Crossrefs

Cf. A060294, A076668 (p=1), A289090 (p=3), A011002 (p=4), A011350 (p=6).

Programs

  • PARI
    // General code, for any p > 0:
    r(p) = (sqrt(2/Pi)^(p%2)*prod(k=0,(p-2)\2,p-1-2*k))^(1/p);
    a = r(5) // Present instance

Formula

a = r(5), where r(p) = ((p-1)!!*sqrt(2/Pi))^(1/p).
a = (8*A076668)^(1/5).

A179615 Continued fraction for 3^(1/4).

Original entry on oeis.org

1, 3, 6, 9, 1, 1, 2, 1, 2, 1, 2, 5, 1, 12, 5, 1, 4, 1, 13, 1, 6, 1, 22, 1, 8, 21, 3, 142, 1, 1, 2, 1, 2, 2, 7, 1, 2, 1, 1, 1, 5, 3, 1, 1, 2, 1, 1, 3, 1, 1, 1, 1, 106, 1, 1, 1, 1, 1, 1, 7, 1, 22, 1, 71, 1, 4, 2, 1, 3, 1, 2, 2, 1, 4, 1, 2, 2, 2, 2, 1, 2, 82, 1, 3, 1, 4, 1, 30, 1, 3, 1, 2, 1, 1, 1, 16, 1, 2
Offset: 0

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Author

Keywords

Comments

3^(1/4) = 1.31607401295249246... (see A011002)

Crossrefs

Cf. A011002 (decimal expansion), A179613.

Programs

Extensions

Offset changed by Andrew Howroyd, Jul 07 2024

A379414 a(n) = n + floor(n*s/r) + floor(n*t/r), where r = 3^(1/4), s = 3^(1/2), t = 3^(3/4).

Original entry on oeis.org

3, 7, 11, 15, 19, 23, 28, 31, 35, 40, 44, 47, 52, 56, 59, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 105, 108, 112, 117, 120, 124, 129, 133, 136, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 194, 197, 201, 206, 210, 213, 218, 222, 225, 230
Offset: 1

Views

Author

Clark Kimberling, Jan 18 2025

Keywords

Comments

This sequence and A379415 and A379416 partition the positive integers; see A184812 for a proof.
For each k in A000027, write "a" if k=A379414(n) for some n, "b" if k=A379415(n) for some n, and "c" if k=A379416(n) for some n. Concatenating these letters for k = 1,2,3,... spells the following infinite word:
cbacbcabccabcbacbcacbcabcbcacbacbcabccbacbcabcacbcbacbcacbacbcbacbcacbcabcbaccbacbcabccabcbacbcacbcabcbcacbacbcabccbacbacbcabccbacbcabcacbcba

Crossrefs

Programs

  • Mathematica
    r = 3^(1/4); s = 3^(1/2); t = 3^(3/4);
    Table[n + Floor[n*s/r] + Floor[n*t/r], {n, 1, 120}]  (* A379411 *)
    Table[n + Floor[n*r/s] + Floor[n*t/s], {n, 1, 120}]  (* A379412 *)
    Table[n + Floor[n*r/t] + Floor[n*s/t], {n, 1, 120}]  (* A379413 *)

Formula

a(n) = n + floor(n*r) + floor(n*r^2), where r = 3^(1/4).

A379415 a(n) = n + floor(n*r/s) + floor(n*t/s), where r = 3^(1/4), s = 3^(1/2), t = 3^(3/4).

Original entry on oeis.org

2, 5, 8, 12, 14, 17, 21, 24, 26, 30, 33, 36, 39, 42, 45, 49, 51, 54, 58, 61, 63, 66, 70, 73, 75, 79, 82, 85, 89, 91, 94, 98, 101, 103, 107, 110, 113, 116, 119, 122, 125, 128, 131, 134, 138, 140, 143, 147, 150, 152, 156, 159, 162, 166, 168, 171, 175, 178, 180
Offset: 1

Views

Author

Clark Kimberling, Jan 18 2025

Keywords

Comments

This sequence and A379414 and A379416 partition the positive integers; see A184812 for a proof.

Crossrefs

Programs

  • Mathematica
    r = 3^(1/4); s = 3^(1/2); t = 3^(3/4);
    Table[n + Floor[n*s/r] + Floor[n*t/r], {n, 1, 120}]  (* A379414 *)
    Table[n + Floor[n*r/s] + Floor[n*t/s], {n, 1, 120}]  (* A379415 *)
    Table[n + Floor[n*r/t] + Floor[n*s/t], {n, 1, 120}]  (* A379416 *)

Formula

a(n) = n + floor(n/r) + floor(n*r), where r = 3^(1/4).

A093604 Decimal expansion of D/2, where D^2 = 3*sqrt(3)/Pi.

Original entry on oeis.org

6, 4, 3, 0, 3, 7, 0, 6, 8, 5, 7, 8, 7, 4, 3, 7, 8, 4, 6, 4, 1, 7, 8, 2, 5, 0, 5, 6, 6, 5, 1, 5, 7, 9, 7, 8, 8, 6, 2, 3, 0, 4, 9, 8, 3, 3, 3, 2, 6, 3, 0, 4, 8, 7, 1, 2, 3, 9, 1, 4, 9, 9, 0, 4, 1, 5, 4, 3, 0, 2, 9, 9, 2, 4, 2, 4, 5, 1, 7, 0, 1, 6, 5, 0, 2, 7, 7, 8, 4, 9, 7, 5, 0, 7, 0, 8, 6, 5, 9, 8, 9, 3, 8, 2, 8, 7, 8, 9, 7, 5, 0, 3, 9, 8, 7, 2, 2, 3, 7, 4
Offset: 0

Views

Author

Lekraj Beedassy, May 14 2004

Keywords

Comments

D/2=sqrt(3*sqrt(3)/Pi)/2 corresponds to the radius of the area-bisecting concentric circle within the unit-sided hexagon.

Examples

			sqrt(3*sqrt(3)/Pi)/2 = 0.6430370685787437846417825056651579788623049833326304871239...
		

Crossrefs

Cf. A097603, A010527, A011002, A087197. - R. J. Mathar, Feb 06 2009

Programs

Extensions

Removed leading zero and adjusted offset - R. J. Mathar, Feb 06 2009
Corrected and extended by Harvey P. Dale, Aug 27 2017

A154605 Decimal expansion of 2/(4th root of 3).

Original entry on oeis.org

1, 5, 1, 9, 6, 7, 1, 3, 7, 1, 3, 0, 3, 1, 8, 5, 0, 9, 4, 6, 6, 2, 3, 7, 5, 5, 0, 1, 3, 0, 9, 0, 9, 0, 6, 7, 0, 7, 9, 3, 5, 4, 6, 8, 9, 7, 7, 7, 4, 6, 2, 0, 6, 3, 7, 2, 2, 2, 5, 7, 7, 3, 0, 7, 4, 0, 0, 6, 4, 4, 4, 6, 6, 3, 4, 2, 0, 9, 4, 5, 4, 3, 1, 8, 8, 8, 2, 1, 2, 2, 8, 3, 3, 0, 0, 7, 4, 3, 1, 3, 9, 3, 3, 0, 2
Offset: 1

Views

Author

Rick L. Shepherd, Jan 12 2009

Keywords

Comments

The side length of an equilateral triangle with area 1.
Quartic number with denominator 3 and minimal polynomial 3x^4 - 16. - Charles R Greathouse IV, Jun 30 2021

Examples

			1.5196713713031850946623755013090906...
		

Crossrefs

Programs

Formula

A154605 = 2/A011002 = 2/(3^(1/4)).

A268604 Decimal expansion of 6/sqrt(sqrt(3)).

Original entry on oeis.org

4, 5, 5, 9, 0, 1, 4, 1, 1, 3, 9, 0, 9, 5, 5, 5, 2, 8, 3, 9, 8, 7, 1, 2, 6, 5, 0, 3, 9, 2, 7, 2, 7, 2, 0, 1, 2, 3, 8, 0, 6, 4, 0, 6, 9, 3, 3, 2, 3, 8, 6, 1, 9, 1, 1, 6, 6, 7, 7, 3, 1, 9, 2, 2, 2, 0, 1, 9, 3, 3, 3, 9, 9, 0, 2, 6, 2, 8, 3, 6, 2, 9, 5, 6, 6, 4, 6, 3, 6, 8, 4
Offset: 1

Views

Author

Stanislav Sykora, Feb 08 2016

Keywords

Comments

This is the smallest possible perimeter index P/sqrt(A), with P being the perimeter and A the enclosed area, among all triangles, and sets of triangles, in the Euclidean plane. The minimum value is attained by a single equilateral triangle. See also A019707.

Examples

			4.559014113909555283987126503927272012380640693323861911667731922...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[6/Sqrt[Sqrt[3]], 10, 100][[1]] (* Bruno Berselli, Feb 09 2016 *)
  • PARI
    a=6/sqrt(sqrt(3))

A011042 Decimal expansion of 4th root of 48.

Original entry on oeis.org

2, 6, 3, 2, 1, 4, 8, 0, 2, 5, 9, 0, 4, 9, 8, 4, 9, 2, 1, 6, 3, 8, 4, 3, 7, 8, 0, 3, 5, 9, 3, 9, 9, 8, 1, 1, 0, 3, 2, 0, 1, 3, 7, 1, 8, 0, 4, 1, 1, 6, 4, 4, 3, 5, 3, 4, 6, 3, 8, 4, 5, 3, 1, 7, 1, 9, 1, 7, 3, 3, 5, 9, 0, 3, 9, 4, 6, 0, 4, 2, 6, 6, 1, 0, 1, 4, 8, 6, 3, 0, 0, 4, 9, 3, 2, 0, 3, 8, 6
Offset: 1

Views

Author

Keywords

Programs

Formula

Equals 2*A011002. [From R. J. Mathar, Feb 04 2009]
Showing 1-10 of 16 results. Next