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A247396
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Number of even numbers in classes of classification of the positive numbers defined in comment in A247395.
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5
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0, 1, 3, 8, 12, 36, 24, 60, 36, 84, 156, 60, 204, 156, 84, 180, 300, 336, 120, 384, 276, 144, 456, 324, 516, 744, 396, 204, 420, 216, 444, 1680, 516, 804, 276, 1440, 300, 924, 960, 660, 1020, 1056, 360, 1860, 384, 780, 396, 2460, 2604, 900, 456, 924, 1416, 480
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OFFSET
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0,3
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COMMENTS
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In the classification every class contains no more than a finite number of numbers with a given least prime divisor.
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LINKS
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FORMULA
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For n>=3, a(n) = (prime(n)^2 - prime(n-1)^2)/2.
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EXAMPLE
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a(6) = (prime(6)^2 - prime(5)^2)/2 = (13^2 - 11^2)/2 = 24. - Indranil Ghosh, Mar 08 2017
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MAPLE
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MATHEMATICA
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a[0] = 0; a[1] = 1; a[2] = 3; a[n_] := (Prime[n]^2 - Prime[n - 1]^2) / 2; Table[a[n], {n, 0, 53}] (* Indranil Ghosh, Mar 08 2017 *)
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PROG
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(PARI) for(n=0, 53, print1(if(n>2, (prime(n)^2 - prime(n - 1)^2)/2, if(n<2, n, 3)), ", ")) \\ Indranil Ghosh, Mar 08 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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