A067106 a(n) = smallest number whose digit product equals n!/m where m is the product of all prime factors > 7 of n! (with multiplicity).

1, 2, 6, 38, 358, 2589, 25789, 257889, 2578899, 45578899, 45578899, 556788899, 556788899, 25567788899, 455577888999, 5557788888999, 5557788888999, 255577888889999, 255577888889999, 5555778888889999, 355557778888889999

Offset

1,2

Links

Table of n, a(n) for n=1..21.

Example

For n = 12 we have n! = 479001600, m = 11 and n!/m = 43545600 = 5*5*6*7*8*8*8*9*9, so a(12) = 556788899.

Prog

(PARI) {for(n=1, 21, f=factor(n!); m=1; for(j=1, matsize(f)[1], if(f[j, 1]<=7, m=m*f[j, 1]^f[j, 2])); s=if(m>1, "", "1"); k=9; while(m>1, d=divrem(m, k); if(d[2]==0, s=concat(k, s); m=d[1], k--)); print1(eval(s), ", "))}

Crossrefs

Sequence in context: A275557 A197972 A068184 * A032111 A013703 A002031

Adjacent sequences: A067103 A067104 A067105 * A067107 A067108 A067109

Keyword

easy,nonn,base

Author

Amarnath Murthy, Jan 07 2002

Extensions

Edited, corrected and extended by Klaus Brockhaus, Jun 17 2003

Status

approved