id:A086520 - OEIS Search Results

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Number of integers strictly greater than (n-Sqrt[n])/2 and strictly less than (n+Sqrt[n])/2.

+0
1

1, 2, 1, 2, 3, 2, 3, 2, 3, 4, 3, 4, 3, 4, 3, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10 (list; graph; listen)

	OFFSET	`2,2`
	COMMENT	`This sequence occurs in quantum mechanics, in the context of counting certain kinds of inseparable states in an n-qubit model.`
	LINKS	`J. S. Pratt, Universality in the entanglement structure of ferromagnets, Phys. Rev. Lett. 93, 237205 (2004)` `J. S. Pratt, Comments on this sequence`
	EXAMPLE	`a(16)=3 because there are three integers between 6 and 10`
	MATHEMATICA	`a[n_] := If[IntegerQ[Sqrt[n]], Sum[1, {m, Ceiling[(n - Sqrt[n])/2] + 1, Floor[(n + Sqrt[n])/2] - 1}], Sum[1, {m, Ceiling[(n - Sqrt[n])/2], Floor[(n + Sqrt[n])/2]}]]`
	CROSSREFS	`Sequence in context: A105499 A005812 A136625 this_sequence A012265 A006641 A115756` `Adjacent sequences: A086517 A086518 A086519 this_sequence A086521 A086522 A086523`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jeff S. Pratt (jpratt(AT)pas.rochester.edu), Sep 10 2003`

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Last modified December 17 23:40 EST 2009. Contains 171025 sequences.

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