A097221 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).

16, 17, 63, 73, 132, 224, 322, 342, 352, 362, 364, 437, 545, 573, 619, 963, 1017, 1117, 1196, 1516, 2163, 2215, 2335, 2435, 2537, 3277, 3514, 3714, 4072, 4513, 4626, 5137, 6475, 8443, 11373, 11593, 11926, 12012, 12026, 12034, 12121, 12126, 12134, 12555

Offset: 1

Author

Farideh Firoozbakht, Aug 05 2004

Keywords

• nonn
• base

Comments

A097220 is a subsequence of this sequence.

Examples

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

Crossrefs

Cf. A097220, A097222.

Programs

PARI

composed(n,a)=my(d=0,k);if(a>=n,return(a==n));while(10^d0&a%k==0&composed(n\10^d,a/k),return(1)));0
isA097221(n)=composed(n,primepi(n))

Extensions

Corrected (2537,3277,4513,4626 were missing), extended, edited, and program added by Charles R Greathouse IV, Apr 23 2010