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A138143
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Triangle read by rows in which row n lists p(1), p(2), ..., p(n), p(n-1), ..., p(1), where p(i) = i-th prime.
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3
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2, 2, 3, 2, 2, 3, 5, 3, 2, 2, 3, 5, 7, 5, 3, 2, 2, 3, 5, 7, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 17, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 17, 19, 17, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 17, 19, 23, 19, 17, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 23, 19, 17, 13, 11, 7, 5, 3, 2
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OFFSET
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1,1
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COMMENTS
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Row n contains 2n-1 terms and each column lists the prime numbers A000040.
Triangle of primes mentioned in A061802.
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LINKS
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EXAMPLE
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Triangle begins:
.............. 2
........... 2, 3, 2
........ 2, 3, 5, 3, 2
..... 2, 3, 5, 7, 5, 3, 2
.. 2, 3, 5, 7,11, 7, 5, 3, 2
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MATHEMATICA
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nn=10; Module[{pr=Prime[Range[nn]], e}, Flatten[Table[e=Take[pr, n]; Join[ e, Reverse[Most[e]]], {n, nn}]]] (* Harvey P. Dale, Mar 14 2015 *)
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CROSSREFS
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KEYWORD
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easy,nonn,tabf
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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