A053989 - OEIS

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A053989

Smallest k such that nk-1 is prime.

3, 2, 1, 1, 4, 1, 2, 1, 2, 2, 4, 1, 8, 1, 2, 2, 4, 1, 2, 1, 2, 2, 6, 1, 6, 4, 2, 3, 6, 1, 2, 1, 4, 2, 4, 2, 2, 1, 6, 2, 4, 1, 6, 1, 2, 3, 6, 1, 2, 3, 2, 2, 4, 1, 2, 3, 2, 3, 6, 1, 8, 1, 4, 2, 6, 2, 6, 1, 2, 2, 4, 1, 14, 1, 2, 2, 4, 3, 2, 1, 8, 2, 4, 1, 6, 3, 2, 3, 16, 1, 2, 4, 6, 3, 4, 2, 2, 1, 2, 2 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	FORMULA	`a(n)=(A038700(n)+1)/n`
	EXAMPLE	`a(5)=4 because the smallest prime in the sequence 5k-1 (4,9,14,19,24...) is 19 when k=4`
	CROSSREFS	`Cf. A034693, A038700.` `Sequence in context: A188316 A197027 A143772 * A097794 A137683 A046225` `Adjacent sequences: A053986 A053987 A053988 * A053990 A053991 A053992`
	KEYWORD	`easy,nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Apr 04 2000`

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Last modified February 17 08:44 EST 2012. Contains 205998 sequences.