login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A222171 Decimal expansion of Pi^2/24. 5
4, 1, 1, 2, 3, 3, 5, 1, 6, 7, 1, 2, 0, 5, 6, 6, 0, 9, 1, 1, 8, 1, 0, 3, 7, 9, 1, 6, 6, 1, 5, 0, 6, 2, 9, 7, 3, 0, 4, 7, 3, 7, 4, 7, 5, 3, 0, 1, 6, 9, 9, 6, 0, 9, 4, 3, 3, 8, 8, 9, 5, 5, 7, 3, 4, 2, 5, 0, 1, 8, 6, 7, 6, 0, 0, 8, 0, 0, 2, 1, 8, 4, 5, 8, 4, 0, 7, 2, 2, 5, 1, 5, 4, 9, 3, 9, 6, 7, 6, 3 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

REFERENCES

George Boros and Victor H. Moll, Irresistible integrals, Cambridge University Press (2006), p. 242.

LINKS

Table of n, a(n) for n=0..99.

FORMULA

Pi^2/24 = Integral_{0, Pi/2} log(sec(x))/tan(x) dx. - Jean-François Alcover

Pi^2/24 = Sum_{k >= 1} 1/(2k)^2. - Geoffrey Critzer, Nov 02 2013

Equals (1/10) * Sum_{k>=1} d(k^2)/k^2, where d(k) is the number of divisors of k (A000005). - Amiram Eldar, Jun 27 2020

EXAMPLE

0.411233516712056609118103791661506297304737475301699609433889557342501867600...

MATHEMATICA

RealDigits[Pi^2/24, 10, 100] // First

PROG

(MAGMA) pi:=Pi(RealField(110)); Reverse(Intseq(Floor(10^100*(pi)^2/24))); // Vincenzo Librandi, Sep 25 2015

CROSSREFS

Cf. A000005, A013679, A111003, A072691, A078471.

Sequence in context: A016526 A247341 A030747 * A325529 A264534 A228489

Adjacent sequences:  A222168 A222169 A222170 * A222172 A222173 A222174

KEYWORD

nonn,cons,easy

AUTHOR

Jean-François Alcover, May 13 2013

EXTENSIONS

Leading 0 term removed (to make offset correct) by Rick L. Shepherd, Jan 01 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 23 18:51 EDT 2020. Contains 337315 sequences. (Running on oeis4.)