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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A132697 Decimal expansion of 7/Pi.

Original entry on oeis.org

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

Views

Author

Omar E. Pol, Aug 26 2007

Keywords

Examples

			2.22816920328653470076437268721520106848243504036639028246734281682455516687917....
		

Crossrefs

Programs

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Dec 02 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

Views

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			9.867606471697510817670793...
		

Crossrefs

Programs

Extensions

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

A233527 Decimal expansion of arctan( 1/(2*Pi) ): opposite angle for a right triangle of equal area to a circle.

Original entry on oeis.org

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

Views

Author

John W. Nicholson, Dec 11 2013

Keywords

Examples

			0.15783119028815886016760874178281892360507124059905106041555796721382...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[ArcTan[1/(2 Pi)], 10, 110][[1]] (* Bruno Berselli, Dec 16 2013 *)
  • PARI
    atan(1/(2*Pi))

Formula

Equals arctan(1/A019692).
Equals A019669 - A233528. [Bruno Berselli, Dec 16 2013]

Extensions

More terms from Ralf Stephan, Dec 16 2013

A110191 Decimal expansion of 1/6 - 1/(2*Pi).

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Jul 15 2005

Keywords

Examples

			0.007511723574771330897...
		

References

  • A. P. Prudnikov, Yu. A. Brychkov, and O. I. Marichev, Integrals and Series, Vol. 1 (Overseas Publishers Association, Amsterdam, 1986), p. 722, section 5.3.5, formula 9.

Crossrefs

Cf. A086201.

Programs

  • Mathematica
    RealDigits[1/6 - 1/(2*Pi), 10, 120, -1][[1]] (* Amiram Eldar, Jun 15 2023 *)
  • PARI
    -1/(2*Pi) + 1/6 \\ Michel Marcus, Jan 11 2016
    
  • PARI
    -suminf(k=1, 1/sin(k*Pi*I)^2) \\ Michel Marcus, Jan 11 2016
    
  • PARI
    suminf(k=1, 1/sinh(k*Pi)^2) \\ Vaclav Kotesovec, May 19 2022

Formula

Equals -Sum_{k>=1} 1/sin(k*Pi*i)^2. - Michel Marcus, Jan 11 2016
Equals Sum_{k>=1} 1/sinh(k*Pi)^2. - Vaclav Kotesovec, May 19 2022

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

Views

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			8.59436692696234813151972322211577554986082086998464...
		

Crossrefs

Programs

A218441 a(n) = A000108(n)*A001764(n).

Original entry on oeis.org

1, 1, 6, 60, 770, 11466, 188496, 3325608, 61866090, 1199333850, 24030289140, 494663027040, 10414559269296, 223487031938800, 4874879691748800, 107852781825352080, 2415945569351185530, 54714061423541554650, 1251237165698155135500, 28864572348777684057000
Offset: 0

Views

Author

Paul D. Hanna, Oct 28 2012

Keywords

Comments

G.f. of A000108, C(x), satisfies: C(x) = 1 + x*C(x)^2;
G.f. of A001764, F(x), satisfies: F(x) = 1 + x*F(x)^3.

Examples

			G.f.: A(x) = 1 + x + 6*x^2 + 60*x^3 + 770*x^4 + 11466*x^5 + 188496*x^6 + ...
		

Crossrefs

Programs

  • Mathematica
    a[n_] := CatalanNumber[n] * Binomial[3*n, n]/(2*n+1); Array[a, 20, 0] (* Amiram Eldar, Apr 26 2025 *)
  • Maxima
    A218441[n]:=binomial(2*n, n)/(n+1)*binomial(3*n, n)/(2*n+1)$
    makelist(A218441[n],n,0,30); /* Martin Ettl, Oct 29 2012 */
  • PARI
    {a(n)=binomial(2*n,n)/(n+1)*binomial(3*n,n)/(2*n+1)}
    for(n=0,25,print1(a(n),", "))
    

Formula

a(n) ~ 3^(3*n+1/2)/(2*Pi*n*(n+1)*(2*n+1)) = A086201*3^(3*n+1/2)/(n*(n+1)*(2*n+1)) (using the Stirling approximation for n!). - A.H.M. Smeets, Dec 31 2022

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

Views

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			4.138028520389278729990977847685373412895950789251867667439350945531316738....
		

Crossrefs

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

Views

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			4.45633840657306940152874537443040213696487008073278056493468563364911033....
		

Crossrefs

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

Views

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.

Crossrefs

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

Views

Author

Omar E. Pol, Aug 31 2007

Keywords

Examples

			5.4112680651244414161420479546654883091716279551755192574206896980024911195637....
		

Crossrefs

Programs

Previous Showing 11-20 of 31 results. Next