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A000099 Let A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.
(Formerly M1374 N0534)
6
1, 2, 5, 10, 20, 24, 26, 41, 53, 130, 149, 205, 234, 287, 340, 410, 425, 480, 586, 840, 850, 986, 1680, 1843, 2260, 2591, 3023, 3024, 3400, 3959, 3960, 5182, 5183, 7920, 9796, 11233, 14883, 15119, 15120, 19593, 21600, 21603, 21604, 22177, 28559, 28560 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

David W. Wilson, Table of n, a(n) for n = 1..200

W. C. Mitchell, The number of lattice points in a k-dimensional hypersphere, Math. Comp., 20 (1966), 300-310.

MATHEMATICA

nmax = 3*10^4; A[n_] := 1 + 4*Floor[Sqrt[n]] + 4*Floor[Sqrt[n/2]]^2 + 8* Sum[Floor[Sqrt[n - j^2]], {j, Floor[Sqrt[n/2]]+1, Floor[Sqrt[n]]}]; V[n_] := Pi*n; P[n_] := A[n] - V[n]; record = 0; A000099 = Reap[For[k = 0; n = 1, n <= nmax, n++, p = Abs[P[n]]; If[p > record, record = p; k++; Sow[n]; Print["a(", k, ") = ", n]; ]]][[2, 1]] (* Jean-Fran├žois Alcover, Feb 03 2016 *)

CROSSREFS

Cf. A000323, A000036, A000092, A000413, A000223.

Sequence in context: A016029 A018327 A285571 * A039690 A243938 A126105

Adjacent sequences:  A000096 A000097 A000098 * A000100 A000101 A000102

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

Entry revised by N. J. A. Sloane, Jun 26 2005

STATUS

approved

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Last modified December 16 08:42 EST 2018. Contains 318158 sequences. (Running on oeis4.)