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A337070
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Number of strict chains of divisors starting with the superprimorial A006939(n).
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12
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OFFSET
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0,2
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COMMENTS
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The n-th superprimorial is A006939(n) = Product_{i = 1..n} prime(i)^(n - i + 1).
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LINKS
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FORMULA
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EXAMPLE
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The a(0) = 1 through a(2) = 16 chains:
1 2 12
2/1 12/1
12/2
12/3
12/4
12/6
12/2/1
12/3/1
12/4/1
12/4/2
12/6/1
12/6/2
12/6/3
12/4/2/1
12/6/2/1
12/6/3/1
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MATHEMATICA
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chern[n_]:=Product[Prime[i]^(n-i+1), {i, n}];
chnsc[n_]:=If[n==1, {{1}}, Prepend[Join@@Table[Prepend[#, n]&/@chnsc[d], {d, Most[Divisors[n]]}], {n}]];
Table[Length[chnsc[chern[n]]], {n, 0, 3}]
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CROSSREFS
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A336571 is the case with distinct prime multiplicities.
A337071 is the version for factorials.
A000142 counts divisors of superprimorials.
A006939 lists superprimorials or Chernoff numbers.
A067824 counts chains of divisors starting with n.
A074206 counts chains of divisors from n to 1.
A317829 counts factorizations of superprimorials.
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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