OFFSET
1,2
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..50
EXAMPLE
For n=1, the only matrix is the matrix of all 1s, which has determinant 0. Hence, a(1)=1.
PROG
(Python)
from itertools import product, groupby, count
.
def det(m):
...a, b, c, d, e, f, g, h, i = m
...return abs(a*(e*i-f*h)-b*(d*i-f*g)+c*(d*h-e*g))
.
def a262719(n):
...s = list(product(range(1, n+1), repeat=9))
...i = 0
...for k, ms in groupby(sorted(s, key=det), key=det):
......if k!=i:
.........return i
......i += 1
...return i
CROSSREFS
KEYWORD
nonn
AUTHOR
Christian Perfect, Sep 28 2015
EXTENSIONS
a(7)-a(41) from Hiroaki Yamanouchi, Oct 17 2015
STATUS
approved