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A067636
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Row 1 of table in A067640.
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1
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2, 20, 210, 2352, 27720, 339768, 4294290, 55621280, 734959368, 9873696560, 134510127752, 1854385377600, 25828939188000, 362995937665200, 5141806953167250, 73343003232628800, 1052697272275341000, 15194039267330154000, 220410039466873456200
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OFFSET
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0,1
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LINKS
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FORMULA
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a(n) = (2*n+2)!*(2*n+4)!/(n!*((n+2)!)^2*(n+3)!). [adapted to offset 0 by Georg Fischer, May 29 2021]
D-finite with recurrence: a(0) = 2, n*(n+2)*(n+3)*a(n) - 4*(n+1)*(2*n+1)*(2*n+3)*a(n-1) = 0 for n >= 1. - Georg Fischer, May 29 2021
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MAPLE
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MATHEMATICA
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RecurrenceTable[{n*(n+2)*(n+3)*a[n] - 4*(n+1)*(2*n+1)*(2*n+3)*a[n-1] == 0, a[0]==2}, a, {n, 0, 16}] (* Georg Fischer, May 29 2021 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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