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%I #9 Jun 30 2024 22:15:10
%S 1,1,17,261,8393,356618,20355656,1498310848,141920467648,
%T 16632516446720,2345863766165536,394823892589979472,
%U 78653652638945445776,18216229760067802231488,4833321599094565894295552,1462259517864407783009737728,498935238969900279377677930496,190227655207141695023381769820864
%N a(n) is the permanent of the symmetric Toeplitz matrix of order n whose element (i,j) equals the |i-j|-th composite or 1 if i = j.
%e a(4) = 8393:
%e [1, 4, 6, 8]
%e [4, 1, 4, 6]
%e [6, 4, 1, 4]
%e [8, 6, 4, 1]
%t Composite[n_Integer]:=FixedPoint[n + PrimePi[ # ] + 1 &, n + PrimePi[n] + 1]; a[n_] := Permanent[Table[If[i == j, 1, Composite[Abs[i - j]]], {i, 1, n}, {j, 1, n}]]; Join[{1},Array[a,17]]
%o (PARI) c(n) = for(k=0, primepi(n), isprime(n++)&&k--); n; \\ A002808
%o a(n) = matpermanent(matrix(n, n, i, j, if (i==j, 1, c(abs(i-j))))); \\ _Michel Marcus_, Jun 27 2024
%Y Cf. A071080 (determinant).
%Y Cf. A374067, A374068, A374070, A374071.
%K nonn
%O 0,3
%A _Stefano Spezia_, Jun 27 2024
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