id:A100395 - OEIS Search Results

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a(n)=q is the smallest prime number such that the greatest prime-divisor of 2q+1=1+2a(n) equals the n-th prime.

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13, 2, 3, 5, 19, 59, 47, 11, 43, 139, 277, 61, 107, 23, 79, 29, 457, 167, 461, 109, 197, 41, 311, 727, 151, 257, 53, 163, 2203, 317, 1637, 479, 347, 223, 1283, 863, 733, 83, 1297, 89, 271, 859, 1061, 1871, 2089, 5591, 557, 113, 1259, 349, 1553, 3253, 1129, 2441 (list; graph; listen)

	OFFSET	`2,1`
	COMMENT	`Offset=2 because p[1]=2 is never a prime factor of an odd number.`
	FORMULA	`a[n]=Min{x; x is prime number; A006530[2x+1]=p[n]=n-th prime number}`
	EXAMPLE	`n=1: a[1]=13 because it is the least prime number such that the greatest prime divisor of 2.13+1=27 equals 3;` `n=2: a[2]=2 because the largest prime divisor of 2.a[2]+1=5 is 5;` `n=6: a[6]=19 since the greatest prime factor of 2.19+1=39=3.13 is 13=p[6].`
	CROSSREFS	`Cf. A006530, A023590, A100394.` `Adjacent sequences: A100392 A100393 A100394 this_sequence A100396 A100397 A100398` `Sequence in context: A010222 A086266 A040166 this_sequence A051310 A010224 A100081`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Dec 16 2004`

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Last modified October 13 02:37 EDT 2008. Contains 145008 sequences.

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