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A112342
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Number of primes between (n-th composite - 1)^2 and (n-th composite)^2.
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1
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2, 2, 3, 4, 3, 4, 5, 4, 6, 5, 6, 7, 7, 6, 9, 8, 7, 8, 8, 10, 9, 10, 9, 10, 9, 12, 11, 11, 12, 11, 13, 13, 15, 10, 11, 15, 12, 13, 11, 12, 17, 16, 13, 17, 15, 14, 16, 15, 17, 13, 15, 17, 17, 18, 22, 14, 23, 13, 20, 20, 17, 16, 21, 22, 18, 20, 20, 19, 23, 21, 21, 22, 23, 21, 22, 21, 21
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n) = A000720(A002808(n)^2) - A000720((A002808(n)-1)^2). - Chandler
Begin with the first prime, compute square root, take floor and add 1. If result is a composite number then begin the count for that composite value. Increment the count until the composite value changes.
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EXAMPLE
| a(1)=2 because for primes 11 and 13, the floor of the square root of both primes is 3. Since 1 is added to each, 3+1=4, for the composite 4 the count is 2.
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PROG
| Same as in A112341 except for line 60: if D<>prmdiv(D)then print B; C; D; "-"
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CROSSREFS
| Cf. A112341.
Sequence in context: A135529 A061282 A064514 * A063712 A185977 A204006
Adjacent sequences: A112339 A112340 A112341 * A112343 A112344 A112345
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KEYWORD
| easy,nonn
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AUTHOR
| Enoch Haga (Enokh(AT)comcast.net), Sep 05 2005
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EXTENSIONS
| Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 06 2005
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