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A122441
Expansion of 2*(sqrt(1+8x)-3)/(sqrt(1+8x)-5).
1
1, -1, 1, -5, 25, -141, 849, -5349, 34825, -232445, 1582081, -10938709, 76616249, -542472685, 3876400305, -27919883205, 202480492905, -1477306676445, 10836099051105, -79861379898165, 591082795606425, -4391625157145805, 32742445489969425, -244889639907014565
OFFSET
0,4
COMMENTS
Row sums of A122440.
FORMULA
a(n) = -hypergeometric([1-n, n], [-n], -2) if n>0. - Peter Luschny, Nov 30 2014
PROG
(Sage)
def a(n):
if n==0: return 1
return -hypergeometric([1-n, n], [-n], -2).simplify()
[a(n) for n in range(21)] # Peter Luschny, Nov 30 2014
CROSSREFS
Cf. A064311.
Sequence in context: A344249 A081683 A064311 * A114870 A222676 A285382
KEYWORD
easy,sign
AUTHOR
Paul Barry, Sep 05 2006
STATUS
approved