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.

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

Adjacent sequences: A005323 A005324 A005325 this_sequence A005327 A005328 A005329

Sequence in context: A094084 A042829 A140896 this_sequence A100600 A076001 A032833

nonn,nice

njas

Corrected by Vladeta Jovovic (vladeta(AT)Eunet.yu), Jul 05 2003

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