cp's OEIS Frontend

A374068 a(n) is the permanent of the symmetric Toeplitz matrix of order n whose element (i,j) equals the |i-j|-th prime or 0 if i = j.

%I A374068 #18 Jul 06 2024 19:48:22
%S A374068 1,0,4,24,529,16100,919037,75568846,9196890092,1491628025318,
%T A374068 317579623173729,86997150829931700,29703399282858184713,
%U A374068 12512837775355494800500,6397110844644502402189404,3875565057688532269985283868,2747710211567246171588232074225,2265312860218073375019946448731300
%N A374068 a(n) is the permanent of the symmetric Toeplitz matrix of order n whose element (i,j) equals the |i-j|-th prime or 0 if i = j.
%C A374068 Conjecture: a(n) is the minimal permanent of an n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal. - _Stefano Spezia_, Jul 06 2024
%e A374068 a(4) = 529:
%e A374068   [0, 2, 3, 5]
%e A374068   [2, 0, 2, 3]
%e A374068   [3, 2, 0, 2]
%e A374068   [5, 3, 2, 0]
%t A374068 a[n_]:=Permanent[Table[If[i == j, 0, Prime[Abs[i - j]]], {i, 1, n}, {j, 1, n}]]; Join[{1},Array[a, 17]]
%o A374068 (PARI) a(n) = matpermanent(matrix(n, n, i, j, if (i==j, 0, prime(abs(i-j))))); \\ _Michel Marcus_, Jun 28 2024
%Y A374068 Cf. A071079 (determinant), A085807, A306457, A318173.
%Y A374068 Cf. A374067, A374069, A374070, A374071.
%K A374068 nonn
%O A374068 0,3
%A A374068 _Stefano Spezia_, Jun 27 2024