A118234 - OEIS

%I #8 Mar 11 2014 01:32:18

%S 0,0,1,2,0,3,2,2,3,6,1,7,3,3,5,10,2,11,5,5,7,14,3,13,7,8,7,18,3,19,10,

%T 9,11,15,5,23,11,11,11,26,5,27,13,11,15,30,7,27,13,15,15,34,8,27,15,

%U 17,19,38,7,39,19,17,21,31,9,43,21,21,15,46,11,47,23,19,23,39,11,51,21,26,27

%N Column 3 of triangle A118233, starting at row 1 to include leading zeros.

%F a(3*n-1) = eulerphi(3*n)/2 - 1.

%o (PARI) {a(n)=local(M=matrix(n+2,n+2,r,c,if(r>=c,if(gcd(r-c+1,c)==1,1,0)))^2);M[n,3]}

%Y Cf. A118233.

%K nonn

%O 1,4

%A _Leroy Quet_, _Paul D. Hanna_, Apr 16 2006