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 19 results. Next

A019673 Decimal expansion of Pi/6.

Original entry on oeis.org

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

Views

Author

Keywords

Comments

From Omar E. Pol, Aug 30 2007: (Start)
Pi/6 = Volume of the inscribed ellipsoid / (Volume of the cuboid (If L1>L2>L3)).
Pi/6 = Volume of the inscribed spheroid / (Volume of the cuboid (If L1>(L2=L3))).
Pi/6 = Volume of the inscribed spheroid / (Volume of the cuboid (If L1<(L2=L3))).
Pi/6 = Volume of the inscribed sphere / (Volume of the regular hexahedron (Or cube)). (End)
Pi/6 = Surface area of the inscribed sphere / (surface area of the regular hexahedron (or cube)). - Omar E. Pol, Nov 13 2007
Decimal expansion of arctan(sqrt(1/3)). - Clark Kimberling, Sep 23 2011
Also, decimal expansion of sum( k>=1, (-120+329*k+568*k^2)/(k*(1+k)*(1+2*k)*(1+4*k)*(3+4*k)*(5+4*k)) ). - Bruno Berselli, Dec 01 2013
Atomic packing factor (APF) of the simple cubic lattice filled with spheres of the same diameter (unique example among chemical elements: polonium crystal). - Stanislav Sykora, Sep 29 2014

Examples

			Pi/6 = 0.5235987755982988730771072305465838140328615665625176368291574...
		

References

  • Ian Stewart, Professor Stewart's Cabinet of Mathematical Curiosities, Basic Books, a member of the Perseus Books Group, NY, 2009, "A Constant Bore", pp. 49-50 & 264-266.

Crossrefs

Cf. APF's of other crystal lattices: A093825 (hcp,fcc), A247446 (diamond cubic).

Programs

Formula

From Amiram Eldar, Aug 15 2020: (Start)
Equals Integral_{x=0..oo} 1/(x^2 + 9) dx.
Equals Integral_{x=0..oo} 1/(9*x^2 + 1) dx. (End)
Pi/6 = Sum_{n >= 1} i/(n*P(n,sqrt(-3))*P(n-1,sqrt(-3))), where i = sqrt(-1) and P(n,x) denotes the n-th Legendre polynomial. The first ten terms of the series gives the approximation Pi/6 = 0.52359877559(52...) correct to 11 decimal places - Peter Bala, Mar 16 2024

A132702 Decimal expansion of 12/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 26 2007

Keywords

Comments

From Bernard Schott, Apr 17 2022: (Start)
For any triangle ABC, (see Crux Mathematicorum):
(b+c)/A + (c+a)/B + (a+b)/C >= (12/Pi) * s,
b*c/(A*(s-a)) + c*a/(B*(s-b)) + a*b/(C*(s-c)) >= (12/Pi) * s,
where (A,B,C) are the angles (measured in radians), (a,b,c) the side lengths of this triangle and s the semiperimeter.
Equality stands iff triangle ABC is equilateral. (End)

Examples

			3.819718634...
		

Crossrefs

Programs

Formula

Equals 2*A132696 = 4*A089491 = 6*A060294. -R. J. Mathar, Jul 29 2024

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Jun 19 2009

A132714 Decimal expansion of 24/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			=7.639437268410976116906420641880689377654062995541909539888032514827...
		

Programs

Formula

24/Pi = Sum_{k>=0} ( (30*k+7)*C(2*k,k)^2*(Hypergeometric2F1[1/2 - k/2, -k/2, 1, 64])/(-256)^k ). - Alexander R. Povolotsky, Dec 20 2012
Another version of this identity is: Sum[(30*k+7) * Binomial[2k,k]^2 * (Sum[Binomial[k-m,m] * Binomial[k,m] * 16^m, {m,0,k/2}])/(256)^k, {k,0,infinity}]. - Alexander R. Povolotsky, Jan 25 2013

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 03 2009

A132721 Decimal expansion of 31/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			9.867606471697510817670793...
		

Programs

Extensions

Terms a(32) and beyond from Andrew Howroyd, Jan 03 2020

A132717 Decimal expansion of 27/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			8.59436692696234813151972322211577554986082086998464...
		

Programs

A132703 Decimal expansion of 13/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			4.138028520389278729990977847685373412895950789251867667439350945531316738....
		

Programs

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 02 2009

A132704 Decimal expansion of 14/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			4.45633840657306940152874537443040213696487008073278056493468563364911033....
		

Programs

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 02 2009
More terms from Harvey P. Dale, Oct 03 2012

A132706 Decimal expansion of 16/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			5.092958178940650744604280427920459585102708663694606359925355....
		

References

  • Bruce C. Berndt, Ramanujan’s Notebooks, Part II, Springer-Verlag, New York, 1989.

Programs

Formula

Equals 4 + Sum_{k>=0} binomial(2*k,k)^2/((k+1)^2*16^k). - Amiram Eldar, May 21 2021
16/Pi = 5 + 1^2/(10 + 3^2/(10 + 5^2/(10 + ...))). See Berndt, Entry 25, p. 140, with n = 0 and x = 5. - Peter Bala, Feb 18 2024

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 02 2009

A132707 Decimal expansion of 17/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			5.4112680651244414161420479546654883091716279551755192574206896980024911195637....
		

Programs

A132709 Decimal expansion of 19/Pi.

Original entry on oeis.org

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

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			6.04788783749202275921758300815554575730946653813734505241135907423807831010....
		

Programs

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 02 2009
Showing 1-10 of 19 results. Next