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A057062
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Let R(i,j) be the infinite square array with antidiagonals 1; 2,3; 4,5,6; ...; the n-th prime is in antidiagonal a(n).
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6
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2, 2, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24, 25, 25
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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The array begins
1 3 6 10 15 ...
2 5 9 14 ...
4 8 13 ...
7 12 ...
11 ...
...
The third prime, 5, is in the 3rd antidiagonal, so a(3) = 3.
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MATHEMATICA
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Table[Round[Sqrt[2*Prime[n]]], {n, 100}] (* T. D. Noe, Dec 03 2011 *)
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PROG
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(Haskell)
a057062 n = a057062_list !! (n-1)
a057062_list = f 1 [1..] where
f j xs = (replicate (sum $ map a010051 dia) j) ++ f (j + 1) xs'
where (dia, xs') = splitAt j xs
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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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