A281090 Number of 2 X 2 matrices with all elements in {0,...,n} and prime permanent.

0, 1, 27, 85, 139, 307, 399, 765, 1043, 1517, 1889, 3021, 3523, 5299, 6269, 7671, 9209, 12729, 14179, 18995, 21307, 24991, 28303, 36261, 39307, 47541, 52833, 61173, 67113, 82125, 86601, 104655, 114695, 128069, 139213, 156653, 165819, 194591, 209753, 230835, 245457, 283887

Offset: 0

Author

Indranil Ghosh, Jan 20 2017

Keywords

• nonn

Examples

			For n = 4, a few of the possible matrices are [0,1;3,3], [0,1;3,4], [0,2;1,0], [0,2;1,1], [0,2;1,2], [2,0;1,1], [2,0;2,1], [2,0;3,1], [2,0;4,1], [2,1;0,1], [4,3;1,1], [4,3;1,2], [4,3;1,4], [4,3;3,1], [4,3;3,2], [3,2;2,3], [3,2;4,1], [3,2;4,3], [3,3;0,1], [3,3;1,0], ... There are 139 possibilities. So, a(4) = 139.
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..1000 (terms 0..151 from Indranil Ghosh)

Crossrefs

Cf. A210000, A281315.

Programs

Python

from sympy import isprime
def t(n):
    s=0
    for a in range(0, n+1):
        for b in range(0, n+1):
            for c in range(0, n+1):
                for d in range(0, n+1):
                    if isprime(a*d+b*c)==True:
                        s+=1
    return s
for i in range(0, 152):
    print(f"{i} {t(i)}")