A147556 - OEIS

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A147556

Largest prime factor of prime(n)-th repunit number.

11, 37, 271, 4649, 513239, 265371653, 5363222357, 1111111111111111111, 11111111111111111111111, 77843839397, 57336415063790604359, 2212394296770203368013, 201763709900322803748657942361 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`The sequence of repunit primes is a subsequence of this sequence.`
	LINKS	`Ray Chandler, Table of n, a(n) for n = 1..58` `Makoto Kamada, Factorizations of 11...11 (Repunit).`
	FORMULA	`a(n) = A006530(A002275(A000040(n))) = A006530(A019328(A000040(n))).`
	EXAMPLE	`Prime(15)=47 and (10^47-1)/9 = 35121409*316362908763458525001406154038726382279, so a(15)=316362908763458525001406154038726382279.`
	CROSSREFS	`Cf. A004022, A147555.` `Sequence in context: A075024 A152094 A160623 * A201312 A120833 A034969` `Adjacent sequences: A147553 A147554 A147555 * A147557 A147558 A147559`
	KEYWORD	`nonn`
	AUTHOR	`Farideh Firoozbakht (mymontain(AT)yahoo.com), Dec 26 2008`
	EXTENSIONS	`Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 06 2011`

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Last modified February 15 14:37 EST 2012. Contains 205822 sequences.