A108088 - OEIS

A108088

Decimal expansion of 1/(1+1/(1+2/(1+3/(1+4/(1+5/(1+...)))))).

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

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OFFSET

0,1

COMMENTS

Term of Ramanujan's formula (see A059444 and A060196).

REFERENCES

S. R. Finch, "Mathematical Constants", Cambridge, pp. 423-428.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..5000

FORMULA

Equals sqrt(Pi*e/2)*erfc(1/sqrt(2)), where erfc is the complementary error function. - Daniel Forgues, Apr 14 2011

Also equals Integral_{-infinity..infinity} (1/sqrt(2*Pi))*exp(-x^2/2)/(1+x^2) dx, where the integrand is normal PDF times Cauchy PDF. - Jean-François Alcover, Apr 28 2015

EXAMPLE

0.6556795424187984715438712307308112833992823328704...

MATHEMATICA

RealDigits[Sqrt[Pi*E/2]*Erfc[1/Sqrt[2]], 10, 111][[1]]

PROG

(PARI) sqrt(Pi*exp(1)/2)*erfc(1/sqrt(2)) \\ G. C. Greubel, Feb 03 2017

CROSSREFS

Cf. A111129.

Sequence in context: A199791 A199600 A021608 * A137727 A010497 A167918

Adjacent sequences: A108085 A108086 A108087 * A108089 A108090 A108091

KEYWORD

nonn,cons

AUTHOR

Philippe Deléham, Jun 21 2005

STATUS

approved