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A173706
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Triangle read by rows, of p*(q-1) for primes p, q with p>q.
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2
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3, 5, 10, 7, 14, 28, 11, 22, 44, 66, 13, 26, 52, 78, 130, 17, 34, 68, 102, 170, 204, 19, 38, 76, 114, 190, 228, 304, 23, 46, 92, 138, 230, 276, 368, 414, 29, 58, 116, 174, 290, 348, 464, 522, 638, 31, 62, 124, 186, 310, 372, 496, 558, 682, 868
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OFFSET
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1,1
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COMMENTS
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The crossing number of a (p,q) torus knot with p > q => 2 is p*(q-1) [Proposition 10.5.3 in Cromwell]
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REFERENCES
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Peter R. Cromwell, Knots and Links, Cambridge University Press, November 15, 2004, p. 255.
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LINKS
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FORMULA
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EXAMPLE
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3;
5, 10;
7, 14, 28;
11, 22, 44, 66;
13, 26, 52, 78, 130;
17, 34, 68, 102, 170, 204;
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MAPLE
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T:= (i, j)-> ithprime(i) *(ithprime(j)-1): seq (seq (T(n, k), k=1..n-1), n=2..11);
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MATHEMATICA
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Table[Prime[i]*(Prime[j] - 1), {n, 2, 10}, {k, 1, n - 1}] // Flatten (* G. C. Greubel, Nov 23 2016 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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