A105465 - OEIS

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A105465

Number of irregular primes less than or equal to the 2^n-th prime.

0, 0, 0, 1, 5, 15, 47, 95, 205, 405, 822, 1625, 3243, 6453, 12798, 25715, 51778, 103315, 206646 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,5`
	COMMENTS	`Limit_{n->inf.} a(n)/2^n = 1-e^(-1/2).`
	MATHEMATICA	`ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # < Prime[2^n] &]], {n, 19}]`
	CROSSREFS	`Cf. A105456, A105460.` `Sequence in context: A079798 A037504 A197237 * A089040 A184262 A126944` `Adjacent sequences: A105462 A105463 A105464 * A105466 A105467 A105468`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 07 2005`

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Last modified February 15 03:59 EST 2012. Contains 205694 sequences.