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A350328
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Numbers k such that pi(k) = Sum_{i=1..k} pi(k*(i-1)+i) - pi(k*(i-1)+i-1).
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1
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1, 5, 21, 23, 25, 33, 81, 85, 115, 127, 141, 164, 253, 273, 283, 285, 291, 343, 385, 441, 471, 495, 505, 565, 577, 711, 807, 921, 1107, 1977, 2175, 2437, 2941, 2943, 3381, 4117, 5541, 6531, 7075, 7497, 8193, 8325, 8923
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OFFSET
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1,2
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COMMENTS
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Numbers with the same number of primes on the top row and along the main diagonal of an n X n square array whose elements are the numbers from 1..n^2, listed in increasing order by rows (see example).
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LINKS
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FORMULA
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EXAMPLE
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5 is in the sequence since there are 3 primes in the top row and 3 primes along the main diagonal of the 5 X 5 array below.
[1 2 3 4 5]
[6 7 8 9 10]
[11 12 13 14 15]
[16 17 18 19 20]
[21 22 23 24 25]
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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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