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A083696 a(n)=Sum[Prod(2^n-k),(k=0,2r-1)]5^r/(2r)!,(r=0,2^(n-1)). 1
1, 6, 56, 6016, 72318976, 10460064284409856, 218825889667954898996994670329856, 95769539977943941232017762100658986141884645207653888255921750016 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

a(n)/A083697(n) converges to sqrt(5). a(n)=a(n-1)^2+5*A083697(n-1)^2. Similar to A081459: a(n) is the numerator of the same mapping f(r)=(1/2)(r+5/r) but with initial value r=1.

MATHEMATICA

Table[Sum[Product[2^n - k, {k, 0, 2*r - 1}]k^r/(2*r)!, {r, 0, 2^(n - 1)}], {n, 0, 8}]

CROSSREFS

Sequence in context: A122743 A137032 A053421 * A181430 A001593 A124546

Adjacent sequences:  A083693 A083694 A083695 * A083697 A083698 A083699

KEYWORD

easy,nonn

AUTHOR

Mario Catalani (mario.catalani(AT)unito.it), May 22 2003

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Last modified February 14 16:48 EST 2012. Contains 205635 sequences.