%I #4 Mar 30 2012 17:37:42

%S 16,17,63,73,132,224,322,342,352,362,364,437,545,573,619,963,1017,

%T 1117,1196,1516,2163,2215,2335,2435,2537,3277,3514,3714,4072,4513,

%U 4626,5137,6475,8443,11373,11593,11926,12012,12026,12034,12121,12126,12134,12555

%N Numbers n such that for some k and a_1,a_2,...,a_k the concatenation of the a_i is equal to n and their product is equal to pi(n).

%C A097220 is a subsequence of this sequence.

%e 90942236 is in the sequence because Pi(90942236)=909*42*23*6 in fact a1=909, a2=42, a3=23 & a4=6.

%o (PARI) composed(n,a)=my(d=0,k);if(a>=n,return(a==n));while(10^d<n,k=n%10^d++;if(k>0&a%k==0&composed(n\10^d,a/k),return(1)));0

%o isA097221(n)=composed(n,primepi(n))

%Y Cf. A097220, A097222.

%K nonn,base

%O 1,1

%A _Farideh Firoozbakht_, Aug 05 2004

%E Corrected (2537,3277,4513,4626 were missing), extended, edited, and program added by _Charles R Greathouse IV_, Apr 23 2010