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Search: id:A124448
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| A124448 |
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Riordan array (sqrt(1+4x^2)-2x, (1+2x-sqrt(1+4x^2))/2). |
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+0
2
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| 1, -2, 1, 2, -3, 1, 0, 4, -4, 1, -2, -1, 7, -5, 1, 0, -4, -4, 11, -6, 1, 4, 2, -6, -10, 16, -7, 1, 0, 8, 8, -6, -20, 22, -8, 1, -10, -5, 11, 19, -1, -35, 29, -9, 1, 0, -20, -20, 7, 34, 13, -56, 37, -10, 1, 28, 14, -26, -46, -12, 49, 41, -84
(list; table; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums are A105523 (expansion of 1-xc(-x^2) where c(x) is the g.f. of A000108). Inverse of A106195. Product of A007318 and A124448 is inverse of A053538.
A124448*A007318 = A106180, as infinite lower triangular matrices . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 16 2007
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EXAMPLE
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Triangle begins
1,
-2, 1,
2, -3, 1,
0, 4, -4, 1,
-2, -1, 7, -5, 1,
0, -4, -4, 11, -6, 1,
4, 2, -6, -10, 16, -7, 1,
0, 8, 8, -6, -20, 22, -8, 1
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CROSSREFS
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Sequence in context: A082501 A132815 A094646 this_sequence A138243 A131796 A131797
Adjacent sequences: A124445 A124446 A124447 this_sequence A124449 A124450 A124451
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KEYWORD
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easy,sign,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Nov 01 2006
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