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A104551 Expansion of x/((1-x)sqrt(1+4x^2)). +0
1
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; listen)
OFFSET

0,6

COMMENT

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: A050350 A147266 A147152 this_sequence A100746 A050341 A140360

Adjacent sequences: A104548 A104549 A104550 this_sequence A104552 A104553 A104554

KEYWORD

easy,sign

AUTHOR

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

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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