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A356492
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a(n) is the determinant of a symmetric Toeplitz matrix M(n) whose first row consists of prime(n), prime(n-1), ..., prime(1).
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3
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1, 2, 5, 51, 264, 19532, -11904, 1261296, -2052864, 70621632, 24618221568, 3996020736, 743171562496, 24567175118848, -1257930752000, 864893030400, 12289833785344000, 1099483729459478528, 100515455071223808, 757166323365314560, 6294658173770137600, 7801939905505132544
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OFFSET
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0,2
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COMMENTS
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Conjecture: a(n) is prime only for n = 1 and 2.
Conjecture is true because a(n) is even for n >= 4. This is because all but two rows of the matrix consist of odd numbers. - Robert Israel, Oct 13 2023
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LINKS
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FORMULA
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EXAMPLE
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For n = 1 the matrix M(1) is
2
with determinant a(1) = 2.
For n = 2 the matrix M(2) is
3, 2
2, 3
with determinant a(2) = 5.
For n = 3 the matrix M(3) is
5, 3, 2
3, 5, 3
2, 3, 5
with determinant a(3) = 51.
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MAPLE
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f:=proc(n) uses LinearAlgebra; local i;
Determinant(ToeplitzMatrix([seq(ithprime(i), i=n..1, -1)], symmetric));
end proc:
q(0):= 1:
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MATHEMATICA
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k[i_]:=Prime[i]; M[ n_]:=ToeplitzMatrix[Reverse[Array[k, n]]]; a[n_]:=Det[M[n]]; Join[{1}, Table[a[n], {n, 21}]]
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PROG
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(PARI) a(n) = matdet(apply(prime, matrix(n, n, i, j, n-abs(i-j)))); \\ Michel Marcus, Aug 12 2022
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CROSSREFS
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Cf. A033286 (trace of the matrix M(n)), A356484 (hafnian of the matrix M(2*n)), A356493 (permanent of the matrix M(n)).
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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