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A104551 Expansion of x/((1-x)sqrt(1+4x^2)). 0
0, 1, 1, -1, -1, 5, 5, -15, -15, 55, 55, -197, -197, 727, 727, -2705, -2705, 10165, 10165, -38455, -38455, 146301, 146301, -559131, -559131, 2145025, 2145025, -8255575, -8255575, 31861025, 31861025 (list; graph; refs; listen; history; internal format)
OFFSET

0,6

COMMENTS

A transformation of the Fibonacci numbers A000045 by the Riordan array (1/sqrt(1+4x^2), (sqrt(1+4x^2)-1)/(2x)).

FORMULA

a(n)=sum{k=0..n, (sin(pi*k/2)+cos(pi*k)/2+1/2)C(k-1, (k-1)/2)(1-(-1)^k)/2}.

CROSSREFS

Cf. A054108.

Sequence in context: A147152 A189976 A188272 * A100746 A185785 A185905

Adjacent sequences:  A104548 A104549 A104550 * A104552 A104553 A104554

KEYWORD

easy,sign

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Mar 14 2005

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Last modified February 16 10:28 EST 2012. Contains 205904 sequences.