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A364163
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Least number k such that average of {prime(i) | k - n <= i <= k + n} is prime(k), or -1 if no such number exists.
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0
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1, 3, 22, 7, 94, 16, 20, 10, 12, 166, 727, 40, 37, 71, 702, 56, 41, 76, 33, 424, 314, 133, 71, 726, 241, 35, 618, 205, 78, 138, 1096, 1096, 111, 49, 512, 2006, 5790, 504, 2634, 1497, 199, 1344, 181, 2404, 2237, 162, 241, 470, 667, 81, 106, 2940, 209, 209, 5549
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OFFSET
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0,2
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LINKS
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FORMULA
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EXAMPLE
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a(0) = 1, because 2/1 = 2 = prime(1), and no lesser number satisfies this.
a(1) = 3, because (3+5+7)/3 = 5 = prime(3), and no lesser number satisfies this.
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PROG
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(PARI) a(n) = my(k=n+1); while(sum(i=k-n, k+n, prime(i)) != (2*n+1)*prime(k), k++); k; \\ Michel Marcus, Jul 12 2023
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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