id:A071561 - OEIS Search Results

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Numbers n such that there are no middle divisors of n (A071090).

+0
3

3, 5, 7, 10, 11, 13, 14, 17, 19, 21, 22, 23, 26, 27, 29, 31, 33, 34, 37, 38, 39, 41, 43, 44, 46, 47, 51, 52, 53, 55, 57, 58, 59, 61, 62, 65, 67, 68, 69, 71, 73, 74, 75, 76, 78, 79, 82, 83, 85, 86, 87, 89, 92, 93, 94, 95, 97, 101, 102, 103, 105, 106, 107, 109, 111, 113, 114 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Conjecture: the lim n-> oo, the number of n's which have no middle divisor / n -> > 3/4.`
	MATHEMATICA	`f[n_] := Plus @@ Select[ Divisors[n], Sqrt[n/2] <= # < Sqrt[n*2] &]; Select[ Range[125], f[ # ] == 0 &]`
	CROSSREFS	`Cf. A071090, A071562, A071563.` `Sequence in context: A062886 A133452 A140607 this_sequence A138968 A108052 A046868` `Adjacent sequences: A071558 A071559 A071560 this_sequence A071562 A071563 A071564`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), May 30 2002`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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