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A105723
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a(n) = 3^n - (-1)^n.
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9
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0, 4, 8, 28, 80, 244, 728, 2188, 6560, 19684, 59048, 177148, 531440, 1594324, 4782968, 14348908, 43046720, 129140164, 387420488, 1162261468, 3486784400, 10460353204, 31381059608, 94143178828, 282429536480, 847288609444, 2541865828328, 7625597484988
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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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MATHEMATICA
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PROG
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(Sage) [3^n - (-1)^n for n in range(30)] # G. C. Greubel, Nov 21 2018
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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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