OFFSET
1,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..35
EXAMPLE
a(3)=2 because phi(0)=0, phi(1)=phi(2)=1 and so the matrix is [[0,1,1],[1,0,1],[1,1,0]] with permanent 2.
MAPLE
with(numtheory): with(linalg): p:=(i, j)->phi(abs(i-j)): seq(permanent(matrix(n, n, p)), n=1..16); # Emeric Deutsch, Dec 17 2004
MATHEMATICA
a[n_] := Permanent[Table[EulerPhi[Abs[i-j]], {i, 1, n}, {j, 1, n}]]; Table[ an = a[n]; Print["a(", n, ") = ", an]; an, {n, 1, 17}] (* Jean-François Alcover, Jan 07 2016 *)
PROG
(PARI)
aph(n)={n=abs(n); if(n>0, eulerphi(n), 0); }
a(n)=matpermanent(matrix(n, n, r, c, aph(r-c)));
vector(23, n, a(n)) \\ Joerg Arndt, Aug 15 2019
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 19 2003
EXTENSIONS
More terms from Emeric Deutsch, Dec 17 2004
STATUS
approved