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A070808 Sum(((-1)^k*binomial(4*n,k)),k=n..2*n). 0
1, 2, 42, 407, 6890, 88502, 1385727, 19762290, 303169770, 4514031830, 69135179542, 1050132147077, 16141218975167, 247800513084152, 3825796483371170, 59118992260132532, 916434202205565162 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..16.

FORMULA

1/2*(-1)^(2*n)*binomial(4*n, 2*n)+1/4*(-1)^n*binomial(4*n, n)

MATHEMATICA

Table[Sum[(-1)^k Binomial[4n, k], {k, n, 2n}], {n, 0, 20}] (* Harvey P. Dale, Nov 20 2014 *)

CROSSREFS

Sequence in context: A048373 A066563 A202865 * A229474 A157056 A180425

Adjacent sequences:  A070805 A070806 A070807 * A070809 A070810 A070811

KEYWORD

easy,nonn

AUTHOR

Sebastian Gutierrez and Sarah Kolitz (skolitz(AT)mit.edu), May 15 2002

STATUS

approved

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Last modified September 16 08:18 EDT 2021. Contains 347469 sequences. (Running on oeis4.)