A172315 - OEIS

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A172315

Primes of the form 2^i*3^j - 1 with i + j = 13.

8191, 27647, 62207, 139967, 314927, 472391, 1062881 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`Note that bases 2 = prime(1), 3 = prime(2)` `13 = prime(2 x 3) = prime(prime(1) x prime(2))` `Smallest term 8191 is the 5th Mersenne prime` `It is a finite "FUN" sequence with 7 = prime(4) terms`
	REFERENCES	`Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983`
	LINKS	`Table of n, a(n) for n=1..7.`
	EXAMPLE	`8191 = 2^13 - 1 = prime(1028)` `27647 = 2^10 x 3^3 - 1 = prime(3016) = prime(2^3 x 13 x 29)` `62207 = 2^8 x 3^5 - 1 = prime(6253) = prime(13^ 2 x 37)` `139967 = 2^6 x 3^7 - 1 = prime(13005)` `314927 = 2^4 x 3^9 - 1 = prime(27191), index is prime(2978)` `472391 = 2^3 x 3^10 - 1 = prime(39419), index is prime(4150)` `1062881 = 2 x 3^12 - 1 = prime(83024)`
	CROSSREFS	`Cf. A005105, A168385, A168349` `Sequence in context: A108093 A051334 A145592 * A103902 A075960 A011563` `Adjacent sequences: A172312 A172313 A172314 * A172316 A172317 A172318`
	KEYWORD	`fini,full,nonn`
	AUTHOR	`Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Jan 31 2010`
	STATUS	`approved`

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Last modified May 19 07:18 EDT 2013. Contains 225429 sequences.