A085510 Permanent of the n X n matrix whose element (i,j) equals phi(|i-j|).

0, 1, 2, 16, 150, 2757, 56252, 1843637, 71277004, 3592359440, 197924252436, 14915743198773, 1183551535975484, 123024814715081453, 13742505172992983210, 1747020721154054373156, 240574984100927602314902

Offset: 1

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 19 2003

Keywords

• nonn
• hard

Examples

			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.
		

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 1..35

Crossrefs

Cf. A071083.

Programs

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 *)

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

Extensions

More terms from Emeric Deutsch, Dec 17 2004