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A370634
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A135507(n) is the product of the first n terms of this sequence.
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2
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1, 4, 5, 3, 3, 3, 9, 4, 3, 3, 13, 3, 3, 9, 3, 3, 19, 3, 3, 3, 9, 13, 25, 3, 3, 3, 3, 9, 31, 3, 3, 4, 13, 19, 9, 3, 39, 3, 3, 3, 43, 9, 3, 13, 3, 25, 49, 3, 3, 3, 19, 3, 55, 3, 3, 3, 3, 31, 61, 3, 3, 3, 3, 3, 3, 3, 69, 19, 3, 3, 73, 3, 3, 39, 3, 3, 3, 3, 81, 3
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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For n > 1, 3 <= a(n) <= n+2.
For p = A001359(i) such that gcd(a(p-1), p) = 1, a(p) = p+2 = A006512(i).
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EXAMPLE
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Table of first 20 terms of this sequence and S = A135507.
n S(n) a(n)
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1 1 1
2 4 4
3 20 5
4 60 3
5 180 3
6 540 3
7 4860 9
8 19440 4
9 58320 3
10 174960 3
11 2274480 13
12 6823440 3
13 20470320 3
14 184232880 9
15 552698640 3
16 1658095920 3
17 31503822480 19
18 94511467440 3
19 283534402320 3
20 850603206960 3
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MATHEMATICA
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nn = 120; j = 1; {1}~Join~Reap[Do[k = 2 j + LCM[j, i]; Sow[k/j]; j = k, {i, 2, nn}] ][[-1, 1]]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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