A326421 Least numbers k such that A088534(k) is nondecreasing.

0, 1, 3, 4, 7, 9, 12, 13, 16, 19, 21, 25, 27, 28, 31, 36, 37, 39, 43, 48, 49, 91, 133, 147, 169, 196, 217, 247, 259, 273, 301, 343, 361, 364, 399, 403, 427, 441, 469, 481, 507, 511, 532, 553, 559, 588, 589, 637, 931, 1183, 1519, 1729, 2821, 3367

Offset

1,3

Comments

Least squared radius of a circle around a grid point of the hexagonal 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 hexagonal lattice with smaller radius. a(1) = 0 by convention.

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..163

Prog

(PARI) \\ after M. F. Hasler's A088534(n, d)
r2=0; for(k=0, 3500, my(a088534=sum(x=0, sqrt(k\3), sum(y=max(x, sqrtint(k-x^2)\2), sqrtint(k-2*x^2), x^2+x*y+y^2==k))); if(a088534>=r2, r2=a088534; print1(k, ", ")))

Crossrefs

Cf. A003136, A088534, A118886, A230655, A326311.

Sequence in context: A352274 A035238 A003136 * A034022 A329963 A198772

Adjacent sequences: A326418 A326419 A326420 * A326422 A326423 A326424

Keyword

nonn

Author

Hugo Pfoertner, Sep 12 2019

Status

approved