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A099935 Decimal expansion of sum(k>=0,(-1)^(k+1)*A000045(k)/k!). 2
7, 4, 1, 0, 2, 7, 9, 2, 1, 5, 2, 3, 5, 7, 7, 3, 5, 5, 8, 4, 1, 7, 8, 3, 9, 8, 6, 6, 7, 1, 0, 2, 4, 4, 1, 1, 7, 3, 2, 5, 5, 8, 8, 4, 2, 5, 0, 1, 5, 0, 0, 2, 1, 8, 4, 2, 5, 8, 0, 2, 8, 0, 8, 4, 7, 7, 8, 3, 8, 7, 4, 4, 4, 8, 9, 0, 8, 1, 5, 9, 6, 7, 2, 5, 1, 1, 6, 6, 2, 2, 1, 6, 0, 9, 5, 9, 4, 4, 1, 1, 5, 6, 4, 0 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

This number is the coefficient of x in the reduction of e^(-x) by the substitution x^2->x+1; see A193026 and A193010.

LINKS

Table of n, a(n) for n=0..103.

FORMULA

exp(-1/2)*(2/sqrt(5))*sinh(sqrt(5)/2)=sum(k>=0, (-1)^(k+1)*A000045(k)/k!)=0.7410....

EXAMPLE

0.74102792152...

MATHEMATICA

(E^(1+2/GoldenRatio)-1) / (E^GoldenRatio*(2*GoldenRatio-1)) // RealDigits[#, 10, 105]& // First (* Jean-François Alcover, Feb 13 2013 *)

CROSSREFS

Cf. A098689.

Sequence in context: A199955 A196624 A157413 * A082665 A011101 A021935

Adjacent sequences:  A099932 A099933 A099934 * A099936 A099937 A099938

KEYWORD

cons,nonn

AUTHOR

Benoit Cloitre, Nov 12 2004

STATUS

approved

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Last modified May 25 05:37 EDT 2013. Contains 225644 sequences.