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Number of points in the hexagonal lattice A_2 on the circle centered at the origin with squared radius A230655(n).
2

%I #23 May 20 2021 22:50:16

%S 1,6,12,18,24,36,48,54,72,96,108,144,192,216,288,384,432,576,648,768,

%T 864,960,1152,1296,1536,1728,1920,2304,2592,3072,3456,3840,4608,5184,

%U 6144,6912,7680,9216,10368,12288,13824,15360,18432,20736,23040,24576,27648

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

%C Record values of A004016.

%H Jianing Song, <a href="/A344471/b344471.txt">Table of n, a(n) for n = 1..247</a>

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

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

%e 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.

%o (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

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

%Y Cf. A071385 (similar sequence).

%K nonn

%O 1,2

%A _Jianing Song_, May 20 2021