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A326311
Least numbers k such that A004018(k) is nondecreasing.
2
0, 1, 2, 4, 5, 10, 13, 17, 20, 25, 50, 65, 85, 125, 130, 145, 170, 185, 205, 221, 250, 260, 265, 290, 305, 325, 425, 650, 725, 845, 850, 925, 1025, 1105, 1625, 1885, 2125, 2210, 2405, 2465, 2665, 3145, 3250, 3445, 3485, 3625, 3770, 3965, 4225, 5525
OFFSET
1,3
COMMENTS
Least squared radius of a circle around a grid point of the square lattice such that the number of grid points on this circle is not smaller than the number of grid points on any circle around a grid point of the square lattice with smaller radius. a(1) = 0 by convention.
LINKS
PROG
(PARI) r2=0; for(k=0, 6000, my(a004018 = if( k<1, k==0, 4 * sumdiv( k, d, (d%4==1) - (d%4==3)))); if(a004018>=r2, r2=a004018; print1(k, ", ")))
(Julia) using Nemo
function A326311List(len)
R, x = PolynomialRing(ZZ, "x")
e = theta_qexp(2, len, x)
L = [coeff(e, j) for j in 0:len - 1]
m = ZZ(0)
[n - 1 for (n, l) in enumerate(L) if l == (m = max(m, l))]
end
A326311List(1000) |> println # Peter Luschny, Sep 12 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Sep 11 2019
STATUS
approved