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A015018
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q-factorial numbers for q=-5.
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1
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1, -4, -84, 8736, 4551456, -11851991424, -154324780331904, 10047160498728278016, 3270561732706527788046336, -5323179358400075453935368658944, -43320145405426340445710562789228109824, 1762701221841919957075369153792221868461981696
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OFFSET
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1,2
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..50
Index entries for sequences related to factorial numbers
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FORMULA
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Prod_{k=1}^{n} (q^k - 1) / (q - 1).
a(1) = 1, a(n) = ((-5)^n - 1)*a(n-1)/(-6). - Vincenzo Librandi, Oct 26 2012
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MATHEMATICA
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RecurrenceTable[{a[1]==1, a[n]==(((-5)^n - 1) * a[n-1])/(-6)}, a, {n, 15}] (* Vincenzo Librandi, Oct 26 2012 *)
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PROG
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(Magma) [n le 1 select 1 else ((-5)^n - 1)*Self(n-1)/(-6): n in [1..18]]; // Vincenzo Librandi, Oct 26 2012
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CROSSREFS
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Sequence in context: A012076 A173211 A109901 * A204245 A287248 A225164
Adjacent sequences: A015015 A015016 A015017 * A015019 A015020 A015021
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KEYWORD
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sign,easy
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AUTHOR
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Olivier Gérard
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STATUS
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approved
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