1,3

Number of perumutations p of (1,2,3,...,n) such that k and p(k) are relatively prime for all k in (1,2,3,...,n) - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 23 2002

Coprime matrix M=[m(i,j)] is a square matrix defined by m(i,j)=1 if gcd(i,j)=1 else 0.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

D. M. Jackson, The combinatorial interpretation of the Jacobi identity from Lie algebra, J. Combin. Theory, A 23 (1977), 233-256.

a(2n)=A009679(n)^2 - T. D. Noe (noe(AT)sspectra.com), Feb 10 2007

(PARI) permRWNb(a)=n=matsize(a)[1]; if(n==1, return(a[1, 1])); sg=1; nc=0; in=vectorv(n); x=in; x=a[, n]-sum(j=1, n, a[, j])/2; p=prod(i=1, n, x[i]); for(k=1, 2^(n-1)-1, sg=-sg; j=valuation(k, 2)+1; z=1-2*in[j]; in[j]+=z; nc+=z; x+=z*a[, j]; p+=prod(i=1, n, x[i], sg)); return(2*(2*(n%2)-1)*p) for(n=1, 26, a=matrix(n, n, i, j, gcd(i, j)==1); print1(permRWNb(a)", ")) - Herman Jamke (hermanjamke(AT)fastmail.fm), May 13 2007

Sequence in context: A094084 A042829 A140896 this_sequence A100600 A076001 A032833

Adjacent sequences: A005323 A005324 A005325 this_sequence A005327 A005328 A005329

nonn,nice

N. J. A. Sloane (njas(AT)research.att.com).

Corrected by Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 05 2003

More terms from T. D. Noe (noe(AT)sspectra.com), Feb 10 2007