id:A158724 - OEIS Search Results

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Numbers n such that Prime[n]^2 + 1 is a semiprime.

+0
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2, 3, 5, 8, 10, 17, 18, 20, 22, 26, 32, 34, 42, 46, 58, 70, 75, 80, 87, 89, 98, 104, 105, 115, 116, 121, 131, 133, 142, 152, 158, 167, 173, 175, 177, 180, 182, 189, 190, 193, 194, 218, 228, 232, 237, 239, 242, 267, 271, 280, 282, 291, 296, 326, 333, 337, 339, 347 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`lst={}; Do[If[Plus@@Last/@FactorInteger[Prime[n]^2+1]==2, AppendTo[lst, n]], {n, 0, 6!}]; lst`
	CROSSREFS	`Sequence in context: A022955 A087279 A084907 this_sequence A036961 A122633 A004694` `Adjacent sequences: A158721 A158722 A158723 this_sequence A158725 A158726 A158727`
	KEYWORD	`nonn`
	AUTHOR	`Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 24 2009`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

AT&T Labs Research