OFFSET
1,7
COMMENTS
Traces of these matrices are A221490.
Consider the sequence b(n) defined as 0 when a(n) is 0 and 1 otherwise. What is the value of the limit as n approaches infinity of Sum_{j<=n} b(j)/n provided that this limit exists?
EXAMPLE
For n=4, we consider the first n^2=16 terms of the characteristic function of primes (A010051): (0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0). These terms form a matrix by arranging them in 4 consecutive subsequences of 4 terms each:
0, 1, 1, 0;
1, 0, 1, 0;
0, 0, 1, 0;
1, 0, 0, 0;
and the determinant of this matrix is zero, so a(4)=0.
MATHEMATICA
mat[n_, i_, j_]:=Boole[PrimeQ[(i-1)*n+j]];
a[n_]:=Det@Table[mat[n, i, j], {i, 1, n}, {j, 1, n}];
Table[a[n], {n, 1, 70}]
PROG
(PARI) a(n) = matdet(matrix(n, n, i, j, isprime((i-1)*n+j))); \\ Michel Marcus, Nov 07 2023
(Python)
from sympy import Matrix, isprime
def A367077(n): return Matrix(n, n, [int(isprime(i)) for i in range(1, n**2+1)]).det() # Chai Wah Wu, Nov 16 2023
CROSSREFS
KEYWORD
sign
AUTHOR
Andres Cicuttin, Nov 05 2023
STATUS
approved