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A144843
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a(n) = (6^n - 2^n)^2 / 16.
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1
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1, 64, 2704, 102400, 3748096, 135675904, 4893282304, 176265625600, 6346852335616, 228502162898944, 8226263614357504, 296147719133593600, 10661344637077159936, 383808727914259677184, 13817118056668205154304, 497416296261117961830400, 17906987220053014721069056
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = 81*36^(n-2) + 4^(n-2) - 18*12^(n-2).
G.f.: x*(1+12x)/((1-36x)*(1-4x)*(1-12x)). (End)
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MATHEMATICA
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Table[(6^n-2^n)^2/16, {n, 20}] (* or *) Table[4^(n-2) (3^n-1)^2, {n, 20}] (* Harvey P. Dale, Apr 15 2020 *)
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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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Al Hakanson (hawkuu(AT)gmail.com), Sep 22 2008
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EXTENSIONS
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STATUS
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approved
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