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A245366
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a(n) = 1 + a(n-1) * (a(n-2) - 1) * (a(n-3) - 1) with a(0) = 1, a(1) = 2, a(2) = 3, a(3) = 4.
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2
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1, 2, 3, 4, 9, 55, 1321, 570673, 40677571441, 30641887385179424641, 711307017047678652146384291462042881, 886599784992546696966754646294076268713472764725575212247451289601
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OFFSET
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0,2
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COMMENTS
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Each term is relatively prime to all others except for the pairs (2,4) and (3,9).
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LINKS
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FORMULA
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MATHEMATICA
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a[ n_] := If[ n < 4, Max[1, n+1], a[n] = 1 + a[n-1] (a[n-2] - 1) (a[n-3] - 1)];
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PROG
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(PARI) {a(n) = if( n<4, max(1, n+1), 1 + a(n-1) * (a(n-2) - 1) * (a(n-3) - 1))};
(Magma) I:=[2, 3, 4]; [n le 3 select I[n] else 1 + Self(n-1)*(Self(n-2) - 1)*(Self(n-3) - 1): n in [1..30]]; // G. C. Greubel, Aug 05 2018
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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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