cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A087060 Difference between 2n^2 and the nearest square number.

Original entry on oeis.org

1, 1, 2, 4, 1, 8, 2, 7, 7, 4, 14, 1, 14, 8, 9, 17, 2, 23, 7, 16, 18, 7, 31, 4, 25, 17, 14, 32, 1, 36, 14, 23, 31, 8, 49, 9, 34, 28, 17, 49, 2, 47, 23, 28, 46, 7, 62, 16, 41, 41, 18, 68, 7, 56, 34, 31, 63, 4, 73, 25, 46, 56, 17, 89, 14, 63, 47, 32, 82, 1, 82, 36, 49, 73, 14, 103, 23, 68
Offset: 1

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Author

Jens Voß, Aug 07 2003

Keywords

Comments

max(a(n)/n) approaches sqrt(2), and the indices of the maxima are apparently in A227792. - Ralf Stephan, Sep 23 2013

Examples

			a(10) = 4 because the difference between 2*10^2 = 200 and the nearest square number (196) is 4.
		

Crossrefs

Programs

  • Mathematica
    dnsn[n_]:=Module[{c=2n^2,a,b},a=Floor[Sqrt[c]]^2;b=Ceiling[Sqrt[c]]^2;Min[c-a,b-c]]; Array[dnsn,80] (* Harvey P. Dale, Jul 01 2017 *)

Formula

a(n) = min [A087056(n), A087059(n)] = min [2*n^2 - (floor[n*sqrt(2)])^2, (1 + floor[n*sqrt(2)])^2 - 2*n^2]
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