A129145 - OEIS

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A129145

Alternately odd prime and odd composite numbers.

3, 9, 5, 15, 7, 21, 11, 25, 13, 27, 17, 33, 19, 35, 23, 39, 29, 45, 31, 49, 37, 51, 41, 55, 43, 57, 47, 63, 53, 65, 59, 69, 61, 75, 67, 77, 71, 81, 73, 85, 79, 87, 83, 91, 89, 93, 97, 95, 101, 99, 103, 105, 107, 111, 109, 115, 113, 117, 127, 119, 131, 121, 137, 123, 139, 125 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`For small n's a(2n) >a(2n-1) (that is for small n's, n-th odd prime less than n-th odd composite number), while for large n's a(2n) <a(2n-1) (nth odd prime larger than n-th odd composite number), cf. A129146`
	FORMULA	`a(2n-1)=A065091(n), a(2n) =A071904(n).`
	CROSSREFS	`Cf. A065091, A071904, A129131, A129146.` `Sequence in context: A084496 A084530 A070355 * A064471 A054509 A134001` `Adjacent sequences: A129142 A129143 A129144 * A129146 A129147 A129148`
	KEYWORD	`nonn`
	AUTHOR	`Zak Seidov (zakseidov(AT)gmail.com), Apr 01 2007`

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Last modified February 15 14:52 EST 2012. Contains 205822 sequences.