id:A112342 - OEIS Search Results

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Number of primes between (n-th composite - 1)^2 and (n-th composite)^2.

+0
2

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; listen)

	OFFSET	`1,1`
	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.`
	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.`
	PROGRAM	`Same as in A112341 except for line 60:if D<>prmdiv(D)then print B; C; D; "-"`
	CROSSREFS	`Cf. A112341.` `Sequence in context: A135529 A061282 A064514 this_sequence A063712 A106251 A134478` `Adjacent sequences: A112339 A112340 A112341 this_sequence A112343 A112344 A112345`
	KEYWORD	`easy,nonn`
	AUTHOR	`Enoch Haga (Enokh(AT)comcast.net), Sep 05 2005`
	EXTENSIONS	`Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 06 2005`

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.

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