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A127676 Numerators of partial sums of a series for Pi*sqrt(2)/4. 2
1, 4, 17, 104, 347, 4132, 50251, 47248, 848261, 16882724, 16189889, 357817912, 1856017421, 5753962988, 161845337077, 4871637351712, 5008383140437, 5137314884092, 185568039683479, 181286844605704, 7599727236867089 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

Denominators coincide with A025547(n+1) for n=0..41, but then start to differ. See the W. Lang link. denominator(r(42))=7422822568422519986207785205976075 but the corresponding entry is A025547(43)=126187983663182839765532348501593275.

REFERENCES

R. Ayoub, Euler and the Zeta Function, Am. Math. Monthly 81 (1974) 1067-1086, p. 1077.

E. Maor, Trigonometric Delights, Princeton University Press, 1998, p. 205.

LINKS

W. Lang, Rationals and limit.

FORMULA

a(n)=numerator(r(n)) with the rationals (in lowest terms) r(n):=sum((-1)^floor(k/2)/(2*k+1),k=0..n).

EXAMPLE

Rationals r(n): [1, 4/3, 17/15, 104/105, 347/315, 4132/3465,...].

CROSSREFS

Sequence in context: A024052 A128321 A091635 * A122940 A077386 A004140

Adjacent sequences:  A127673 A127674 A127675 * A127677 A127678 A127679

KEYWORD

nonn,easy,frac

AUTHOR

Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de) Mar 07 2007

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Last modified February 16 20:42 EST 2012. Contains 205962 sequences.