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Search: id:A110491
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| A110491 |
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Expansion of sqrt(1+2x)/sqrt(1-2x). |
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+0
1
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| 1, 2, 4, 24, 144, 1440, 14400, 201600, 2822400, 50803200, 914457600, 20118067200, 442597478400, 11507534438400, 299195895398400, 8975876861952000, 269276305858560000, 9155394399191040000, 311283409572495360000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums of exponential Riordan array [1, arctanh(2x)]. - Paul Barry (pbarry(AT)wit.ie), Apr 17 2008
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FORMULA
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E.g.f. : sqrt((1+2x)/(1-2x)); a(n)=2*n!*binomial(n-1, floor((n-1)/2))+0^n.
The sequence 0,1,0,2,0,4,... has e.g.f. arctanh(x). - Paul Barry (pbarry(AT)wit.ie), Apr 17 2008
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CROSSREFS
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Cf. A000246, A002867.
Adjacent sequences: A110488 A110489 A110490 this_sequence A110492 A110493 A110494
Sequence in context: A119036 A087981 A002875 this_sequence A019010 A009672 A018988
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jul 22 2005
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