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

1,1

Comments

A097220 is a subsequence of this sequence.

Links

Table of n, a(n) for n=1..44.

Example

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

Prog

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

Crossrefs

Cf. A097220, A097222.

Sequence in context: A041524 A042205 A041522 * A097220 A041530 A041528

Adjacent sequences: A097218 A097219 A097220 * A097222 A097223 A097224

Keyword

nonn,base

Author

Farideh Firoozbakht, Aug 05 2004

Extensions

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

Status

approved