A107036 - OEIS

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A107036

Indices of prime Jacobsthal numbers.

3, 4, 5, 7, 11, 13, 17, 19, 23, 31, 43, 61, 79, 101, 127, 167, 191, 199, 313, 347, 701, 1709, 2617, 3539, 5807, 10501, 10691, 11279, 12391, 14479, 42737, 83339, 95369, 117239, 127031, 138937, 141079, 267017, 269987, 374321 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`All terms are prime except a(1) = 4. All prime terms are listed in A000978. - Alexander Adamchuk, Oct 03 2006`
	LINKS	`Table of n, a(n) for n=1..40.`
	FORMULA	`a(n) = A000978(n-1) for n >= 3. - Alexander Adamchuk, Oct 03 2006`
	PROG	`(PARI) is(n)=ispseudoprime((2^n - (-1)^n) / 3) \\ Charles R Greathouse IV, Apr 28 2015`
	CROSSREFS	`Cf. A000978, A001045, A001605.` `Sequence in context: A140826 A081735 A227231 * A001605 A216570 A101762` `Adjacent sequences: A107033 A107034 A107035 * A107037 A107038 A107039`
	KEYWORD	`nonn`
	AUTHOR	`Paul Barry, May 09 2005`
	EXTENSIONS	`More terms from Alexander Adamchuk, Oct 03 2006`
	STATUS	`approved`

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Last modified July 16 12:38 EDT 2021. Contains 346065 sequences. (Running on oeis4.)