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A336964
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Irregular triangle in which first row is 1, n-th row (n > 1) lists distinct prime numbers in the prime tower factorization of n.
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2
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1, 2, 3, 2, 5, 2, 3, 7, 2, 3, 2, 3, 2, 5, 11, 2, 3, 13, 2, 7, 3, 5, 2, 17, 2, 3, 19, 2, 5, 3, 7, 2, 11, 23, 2, 3, 2, 5, 2, 13, 3, 2, 7, 29, 2, 3, 5, 31, 2, 5, 3, 11, 2, 17, 5, 7, 2, 3, 37, 2, 19, 3, 13, 2, 3, 5, 41, 2, 3, 7, 43, 2, 11, 2, 3, 5, 2, 23, 47, 2, 3
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OFFSET
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1,2
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COMMENTS
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The prime tower factorization of a number is defined in A182318.
The n-th row includes the n-th row of A027748.
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LINKS
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EXAMPLE
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Triangle begins:
1 [1]
2 [2]
3 [3]
4 [2]
5 [5]
6 [2, 3]
7 [7]
8 [2, 3]
9 [2, 3]
10 [2, 5]
11 [11]
12 [2, 3]
13 [13]
14 [2, 7]
15 [3, 5]
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PROG
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(PARI) row(n) = { my (f=factor(n), p=f[, 1]~); for (k=1, #f~, if (f[k, 2]>1, p=concat(p, row(f[k, 2]))); ); if (#p==0, [1], Set(p)) }
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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