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

0,3

Links

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

Example

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.

Prog

(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 str(i)+" "+str(t(i))

Crossrefs

Cf. A210000, A281315.

Sequence in context: A043962 A035074 A036925 * A260052 A028993 A262367

Adjacent sequences: A281087 A281088 A281089 * A281091 A281092 A281093

Keyword

nonn

Author

Indranil Ghosh, Jan 20 2017

Status

approved