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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A164106 Decimal expansion of 16*Pi^3/105.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Aug 10 2009

Keywords

Comments

Volume of the 7-dimensional unit sphere.

Examples

			Equals 4.72476597033140116959639086736783164986290111...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[16*Pi^3/105, 10, 100][[1]] (* G. C. Greubel, Apr 09 2017 *)
  • PARI
    16*Pi^3/105 \\ G. C. Greubel, Apr 09 2017

Formula

Equals 16*A091925/105 = A164107/7 .

A308637 Decimal expansion of Pi^3/Zeta(3).

Original entry on oeis.org

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

Views

Author

Seiichi Manyama, Aug 23 2019

Keywords

Crossrefs

-----+---------------------------------
n | Zeta(n)
-----+---------------------------------
2 | Pi^2 / 6 = A013661.
3 | Pi^3 / 25.79... = A002117.
4 | Pi^4 / 90 = A013662.
5 | Pi^5 / A309926 = A013663.
6 | Pi^6 / 945 = A013664.
7 | Pi^7 / A309927 = A013665.
8 | Pi^8 / 9450 = A013666.
9 | Pi^9 / A309928 = A013667.
10 | Pi^10 / 93555 = A013668.
11 | Pi^11 / A309929 = A013669.
12 | 691*Pi^12 / 638512875 = A013670.
...
Cf. A002432, A091925, A276120 (Zeta(3)/Pi^3).

Programs

  • Mathematica
    RealDigits[Pi^3/Zeta[3], 10, 100][[1]] (* Amiram Eldar, Aug 24 2019 *)
  • PARI
    Pi^3/zeta(3)

Formula

Pi^3/Zeta(3) = A091925/A002117.

Extensions

More terms from Amiram Eldar, Aug 24 2019

A164104 Decimal expansion of 8*Pi^2/3.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Aug 10 2009

Keywords

Comments

Surface area of the 5-dimensional unit sphere.

Examples

			Equals 26.318945069571622983558642666336...
		

Crossrefs

Programs

Formula

Equals 5*A164103 = 10 * A019699 * A019692.

Extensions

A-number in formula corrected by R. J. Mathar, Aug 12 2010

A164105 Decimal expansion of Pi^3/6.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Aug 10 2009

Keywords

Comments

Volume of the 6-dimensional unit sphere.

Examples

			Equals 5.1677127800499700292460525111835658670375480943...
		

Crossrefs

Programs

Formula

Equals A091925/6 = A019670*A102753.

A164107 Decimal expansion of 16*Pi^3/15.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Aug 10 2009

Keywords

Comments

Surface area of the 7-dimensional unit sphere.

Examples

			Equals 33.07336179231980818717473607157482154904030780...
		

Crossrefs

Programs

A212003 Decimal expansion of (2*Pi)^3.

Original entry on oeis.org

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

Views

Author

Omar E. Pol, Aug 11 2012

Keywords

Examples

			248.05021344239856140381052053681116161780230852708...
		

Crossrefs

Programs

Formula

Equals Product_{k=1..14, gcd(k,14)==1} Gamma(k/14). - Amiram Eldar, Jun 12 2021

A100322 a(n) is the smallest positive integer k such that the digits of the fractional part of Pi^k begin with n.

Original entry on oeis.org

1, 7, 6, 4, 8, 23, 25, 2, 15, 91, 51, 307, 49, 1, 102, 315, 112, 12, 76, 26, 115, 208, 77, 276, 161, 40, 13, 41, 7, 99, 174, 169, 86, 453, 110, 204, 53, 6, 67, 4, 228, 123, 37, 134, 158, 192, 33, 45, 61, 200, 31, 324, 8, 56, 34, 105, 148, 17, 19, 92, 23, 38, 27, 39, 32, 82
Offset: 1

Views

Author

Mark Hudson (mrmarkhudson(AT)hotmail.com), Nov 16 2004

Keywords

Examples

			Pi^1 = 3.14159..., whose digits after the decimal point begin with 1, so a(1)=1.
Pi^2 = 9.869..., whose digits after the decimal point begin with 8, so a(8)=2.
a(14)=1 because Pi^1 = 3.14....
		

Crossrefs

Programs

  • PARI
    a(n) = my(k=1); while (floor(frac(Pi^k)*10^(1+logint(n, 10))) != n, k++); k; \\ Michel Marcus, Jun 18 2022

A164081 Floor of 2^(n-1) times the surface area of the unit sphere in 2n-dimensional space.

Original entry on oeis.org

6, 39, 124, 259, 408, 512, 536, 481, 378, 264, 166, 94, 49, 24, 10, 4, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Jonathan Vos Post, Aug 09 2009

Keywords

Comments

The rounded values of this real sequence is A164082, the ceiling is A164083.
The surface area of n-dimensional sphere of radius r is n*V_n*r^(n-1); see A072478/A072479.
There are only 17 nonzero terms. - G. C. Greubel, Sep 10 2017

Examples

			Table of approximate real values before taking integer part.
========================
n (2*Pi)^n / (n-1)!
1 6.28318531 = A019692
2 39.4784176 = 2*A164102
3 124.025107 = 4*A091925
4 259.757576 = 8*A164109
5 408.026246
6 512.740903
7 536.941018
8 481.957131
9 378.528246
10 264.262568
11 166.041068
12 94.8424365
13 49.6593836
14 24.00147
15 10.7718345
16 4.5120955
17 1.77189576
18 0.654891141
19 0.228600133
20 0.075596684
========================
		

References

  • J. H. Conway and N. J. A. Sloane, Sphere Packings, Lattices, and Groups, 2nd ed., New York: Springer-Verlag, p. 9, 1993.
  • H. S. M. Coxeter, Regular Polytopes, 3rd ed., New York: Dover, 1973.
  • D. M. Y. Sommerville, An Introduction to the Geometry of n Dimensions, New York: Dover, p. 136, 1958.

Crossrefs

Programs

  • Maple
    A164081 := proc(n) (2*Pi)^n/(n-1)! ; floor(%) ; end: seq(A164081(n),n=1..80) ; # R. J. Mathar, Sep 09 2009
  • Mathematica
    Table[Floor[(2*Pi)^n/(n - 1)!], {n, 1, 100}] (* G. C. Greubel, Sep 10 2017 *)
  • PARI
    for(n=1,100, print1(floor((2*Pi)^n/(n-1)!), ", ")) \\ G. C. Greubel, Sep 10 2017

Formula

a(n) = floor( (2*Pi)^n/(n-1)! ).

Extensions

Definition corrected by R. J. Mathar, Sep 09 2009

A164082 Rounded value of 2^(n-1) times the surface area of the unit sphere in 2n-dimensional space.

Original entry on oeis.org

6, 39, 124, 260, 408, 513, 537, 482, 379, 264, 166, 95, 50, 24, 11, 5, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Jonathan Vos Post, Aug 09 2009

Keywords

Comments

The floor of this real sequence is A164081, the ceiling is A164083.
The surface area of the n-dimensional sphere of radius r is n*V_n*r^(n-1); see A072478/ A072479.
There are 18 nonzero terms in this sequence. - G. C. Greubel, Sep 11 2017

Examples

			Table of approximate real values before rounding up or down:
========================
n ((2*pi)^n) / (n-1)!
1 6.28318531 = A019692
2 39.4784176 = 2*A164102
3 124.025107 = 4*A091925
4 259.757576 = 8*A164109
5 408.026246
6 512.740903
7 536.941018
8 481.957131
9 378.528246
10 264.262568
11 166.041068
12 94.8424365
13 49.6593836
14 24.00147
15 10.7718345
16 4.5120955
17 1.77189576
18 0.654891141
19 0.228600133
20 0.075596684
========================
		

References

  • Conway, J. H. and Sloane, N. J. A. Sphere Packings, Lattices, and Groups, 2nd ed. New York: Springer-Verlag, p. 9, 1993.
  • Coxeter, H. S. M. Regular Polytopes, 3rd ed. New York: Dover, 1973.
  • Sommerville, D. M. Y. An Introduction to the Geometry of n Dimensions. New York: Dover, p. 136, 1958.

Crossrefs

Programs

  • Maple
    A164082 := proc(n) (2*Pi)^n/(n-1)! ; round(%) ; end: seq(A164082(n),n=1..80) ; # R. J. Mathar, Sep 09 2009
  • Mathematica
    Table[Round[(2*Pi)^n/(n - 1)!], {n, 1, 20}] (* G. C. Greubel, Sep 11 2017 *)
  • PARI
    for(n=1,20, print1(round((2*Pi)^n/(n-1)!), ", ")) \\ G. C. Greubel, Sep 11 2017

Formula

a(n) = round(((2*Pi)^n)/(n-1)!).

Extensions

Definition corrected by R. J. Mathar, Sep 09 2009

A193716 Decimal expansion of Pi^3*log(2)/24 - 3*Pi*zeta(3)/16.

Original entry on oeis.org

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

Views

Author

Seiichi Kirikami, Aug 03 2011

Keywords

Comments

The absolute value of the integral {x=0..Pi/2} x^2*log(sin(x )) dx or (d^2/da^2 (integral {x=0..Pi/2} cos(ax)*log(sin(x )) dx)) at a=0. The absolute value of (sum {n=1..infinity} (limit { a -> 0} (d^2/da^2 (sin((a+2n)*Pi/2)/n/(a+2n)))))-(Pi/2)^3*log(2)/3. [Seiichi Kirikami and Peter J. C. Moses]

Examples

			0.18742642282823108026...
		

References

  • I. S. Gradshteyn and I. M. Ryzhik, Table of Integrals, series and Products, 1.441.2, 4th edition, log(sin(x))=-(sum {1..infinity} cos(2nx)/n)-log(2).

Crossrefs

Programs

  • Mathematica
    RealDigits[ N[Pi (2 Pi^2 Log[2] - 9 Zeta[3]) / 48, 105] ][[1]]
  • PARI
    Pi^3*log(2)/24 - 3*Pi*zeta(3)/16 \\ Michel Marcus, Oct 25 2017

Formula

Equals A091925*A002162/24-3*A000796*A002117/16.
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