A344471 Number of points in the hexagonal lattice A_2 on the circle centered at the origin with squared radius A230655(n).

1, 6, 12, 18, 24, 36, 48, 54, 72, 96, 108, 144, 192, 216, 288, 384, 432, 576, 648, 768, 864, 960, 1152, 1296, 1536, 1728, 1920, 2304, 2592, 3072, 3456, 3840, 4608, 5184, 6144, 6912, 7680, 9216, 10368, 12288, 13824, 15360, 18432, 20736, 23040, 24576, 27648

Offset: 1

Author

Jianing Song, May 20 2021

Keywords

• nonn

Comments

Record values of A004016.

Examples

			24 is a term because the circle with radius sqrt(91) centered at the origin hits exactly 24 points in the A_2 lattice, and any circle with radius < sqrt(91) centered at the origin hits fewer than 24 points.
		

Links

• Jianing Song, Table of n, a(n) for n = 1..247

Crossrefs

Cf. A230655, A004016, A002324, A344472, A000005, A344473.

Cf. A071385 (similar sequence).

Programs

PARI

my(v=list_A344473(10^15), rec=0); print1(1, ", "); for(n=1, #v, if(numdiv(v[n])>rec, rec=numdiv(v[n]); print1(6*rec, ", "))) \\ see program for A344473

Formula

a(n) = A004016(A230655(n)).

a(n) = 6*A000005(A230655(n)) = 6*A002324(A230655(n)), n > 1.