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A165421
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a(1) = 1, a(2) = 3, a(n) = product of the previous terms for n >= 3.
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5
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OFFSET
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1,2
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COMMENTS
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Essentially a duplicate of A011764. - N. J. A. Sloane, Oct 06 2009
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..14
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FORMULA
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a(1) = 1, a(2) = 3, a(n) = Product_{i=1..n-1} a(i), n >= 3.
a(1) = 1, a(2) = 3, a(n) = A000244(2^(n-3)) = A011764(n-3) = 3^(2^(n-3)), n >= 3.
a(1) = 1, a(2) = 3, a(3) = 3, a(n) = (a(n-1))^2, n >= 4.
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MATHEMATICA
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a[1]:= 1; a[2]:= 3; a[n_]:= Product[a[j], {j, 1, n-1}]; Table[a[n], {n, 1, 12}] (* G. C. Greubel, Oct 19 2018 *)
nxt[{prd_, a_}]:=Module[{c=prd*a}, {c, prd*a}]; Join[{1, 3}, Rest[ NestList[ nxt, {1, 3}, 10][[All, 1]]]] (* Harvey P. Dale, Jan 31 2022 *)
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PROG
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(PARI) {a(n) = if(n==1, 1, if(n==2, 3, prod(j=1, n-1, a(j))))};
for(n=1, 10, print1(a(n), ", ")) \\ G. C. Greubel, Oct 19 2018
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CROSSREFS
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Sequence in context: A257627 A115564 A122961 * A227432 A100731 A072004
Adjacent sequences: A165418 A165419 A165420 * A165422 A165423 A165424
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KEYWORD
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nonn
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AUTHOR
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Jaroslav Krizek, Sep 17 2009
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STATUS
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approved
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