A394297 - OEIS

A394297

a(n) is the number of unit cubes in the cubic lattice, divided by 2, that have 4 vertices strictly inside and 4 vertices strictly outside the sphere (x-1/2)^2 + (y-1/2)^2 + (z-1/2)^2 = n, i.e., the sphere centered at the deep hole.

0, 3, 3, 7, 7, 15, 15, 3, 3, 27, 27, 31, 31, 19, 19, 15, 15, 39, 39, 51, 51, 51, 51, 27, 27, 43, 43, 43, 43, 91, 91, 39, 39, 63, 63, 87, 87, 51, 51, 75, 75, 87, 87, 87, 87, 91, 91, 67, 67, 91, 91, 115, 115, 111, 111, 111, 111, 111, 111, 87, 87, 135, 135, 87, 87, 135

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

Hugo Pfoertner, Table of n, a(n) for n = 0..10000

FORMULA

a(n) == 3 (mod 4) for n>0.

CROSSREFS

Cf. A005878, A393824, A394294, A394295, A394296, A394298, A394304, A394305, A394306.

Sequence in context: A263794 A344608 A086530 * A357215 A147402 A052551

Adjacent sequences: A394294 A394295 A394296 * A394298 A394299 A394300

KEYWORD

nonn

AUTHOR

Hugo Pfoertner, Mar 15 2026

STATUS

approved