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A016175
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Expansion of 1/((1-6x)(1-12x)).
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3
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1, 18, 252, 3240, 40176, 489888, 5925312, 71383680, 858283776, 10309483008, 123774262272, 1485653944320, 17830024114176, 213973350064128, 2567758564933632, 30813572964188160, 369765696680165376
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = (6^n)*Stirling2(n+2, 2), n >= 0, with Stirling2(n, m) = A008277(n, m).
a(n) = -6^n + 2*12^n.
E.g.f.: (d^2/dx^2)((((exp(6*x)-1)/6)^2)/2!) = -exp(6*x) + 2*exp(12*x).
a(n-1) = ((9+sqrt9)^n - (9-sqrt9)^n)/6. - Al Hakanson (hawkuu(AT)gmail.com), Jan 07 2009
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MATHEMATICA
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LinearRecurrence[{18, -72}, {1, 18}, 20] (* Harvey P. Dale, Nov 25 2013 *)
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PROG
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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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STATUS
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approved
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