A100660 - OEIS

%I #3 Oct 01 2013 17:58:05

%S 6,10,14,15,21,26,30,33,34,35,38,39,42,46,51,55,57,62,65,69,70,74,77,

%T 78,82,85,86,87,91,93,95,102,105,106,111,114,118,119,122,123,129,130,

%U 133,134,138,141,142,143,145,146,155,158,159,161,165,170,177,178,182,183

%N Composite numbers whose prime factors have different digital roots.

%e 399=3*7*19. digital roots = 3,7,1 all different.

%o (PARI) nsamedr2(n) = { local(j); for(j=2,n, if(!isprime(j)&issamedr2(j),print1(j",")) ) } issamedr2(n) = { local(f,a,ln,x,y,dr); f=0; a=ifactor(n); ln=length(a); for(x=1,ln-1, for(y=x+1,ln, if(droot(a[x])==droot(a[y]),return(0)); if(droot(a[x])<>droot(a[y]), f=1,f=0))); if(f==1&ln>1,return(1),return(0)) } droot(n) = \ the digital root of a number. { local(x); x= n%9; if(x>0,return(x),return(9)) } ifactor(n) = \The vector of integer factors of n with multiplicity { local(f,j,k,flist); flist=[]; f=Vec(factor(n)); for(j=1,length(f[1]), for(k = 1,f[2][j],flist = concat(flist,f[1][j]) ); ); return(flist) }

%K base,easy,nonn

%O 1,1

%A _Cino Hilliard_, Jan 02 2005