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A081442
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E.g.f.: cosh(x/sqrt(1-x^2)) (even powers).
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1
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1, 1, 13, 421, 25369, 2449801, 346065061, 67243537453, 17192488230961, 5593309059948049, 2255588021494237501, 1103994926592923677621, 644587811150505183179593, 442516027690815793746696601
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Periodic zeros suppressed.
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FORMULA
| a(n)=(2*n)!*sum(j=0..n, binomial(n-1,n-j)/(2*j)!). [From Vladimir Kruchinin, May 19 2011]
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EXAMPLE
| cosh(x/sqrt(1-x^2)) = 1 + 1/2*x^2 + 13/24*x^4 + 421/720*x^6 + ...
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PROG
| (Maxima)
a(n):=(2*n)!*sum(binomial(n-1, n-j)/(2*j)!, j, 0, n); [From Vladimir Kruchinin, May 19 2011]
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CROSSREFS
| Cf. A081439, A081440.
Sequence in context: A087872 A098890 A012023 * A100872 A012045 A012109
Adjacent sequences: A081439 A081440 A081441 * A081443 A081444 A081445
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Mar 21 2003
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EXTENSIONS
| Definition corrected by Joerg Arndt, May 19 2011.
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