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A128542
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a(n) = ((2n)^(2n) - 1)/((2n+1)*(2n-1)).
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1
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0, 1, 17, 1333, 266305, 101010101, 62350352785, 56984650387477, 72340172838076673, 121815504877079063701, 262801002506265664160401, 706890015246831381773595701, 2319540481478754999041880822337, 9120177155862455275254332279111413
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OFFSET
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0,3
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COMMENTS
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p divides a(p-1) for prime p>3.
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LINKS
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FORMULA
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a(n) = ((2n)^(2n)-1)/((2n+1)*(2n-1)).
a(n) = A048861(2n)/((2n+1)*(2n-1)).
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MATHEMATICA
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Join[{0}, Table[((2n)^(2n)-1)/(4n^2-1), {n, 1, 20}]]
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PROG
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(Magma) [0] cat [((2*n)^(2*n)-1)/(4*n^2 -1): n in [1..20]]; // G. C. Greubel, Jul 11 2019
(Sage) [0]+[((2*n)^(2*n)-1)/(4*n^2 -1) for n in (1..20)] # G. C. Greubel, Jul 11 2019
(GAP) Concatenation([0], List([1..20], n-> ((2*n)^(2*n)-1)/(4*n^2 -1) )); # G. C. Greubel, Jul 11 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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