OFFSET
0,3
COMMENTS
a(n) >= 3*n*A002415(n).
LINKS
Zachary Kaplan, Table of n, a(n) for n = 0..100
Zachary Kaplan, Python program
Mathematics Stack Exchange user Olivier Massicot, How many squares in a three-dimensional n X n X n cartesian grid?
EXAMPLE
For n = 5, one such square has vertex set {(2,1,1), (5,4,1), (4,5,5), (1,2,5)}.
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Kagey, May 14 2020
EXTENSIONS
a(7)-a(12) from Pontus von Brömssen, May 15 2020
a(13)-a(20) from Peter Kagey, Jul 29 2020 via Mathematics Stack Exchange link
Terms a(21) and beyond from Zachary Kaplan, Sep 01 2020, via Mathematics Stack Exchange link
STATUS
approved