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A247187
Numbers containing nine distinct decimal digits (zero is not considered) and having the property that the digits 1 to 5 appear in the order but not the digits 1 to 6.
1
123465789, 123465798, 123465879, 123465897, 123465978, 123465987, 123467589, 123467598, 123467859, 123467895, 123467958, 123467985, 123468579, 123468597, 123468759, 123468795, 123468957, 123468975, 123469578, 123469587, 123469758, 123469785, 123469857, 123469875
OFFSET
1,1
COMMENTS
The sequence is finite and contains 2520 numbers.
To build a such number, first place the digits 1 to 5, and then insert the digit 6 anywhere but not after the digit 5, then the digits 7, 8 and 9. The order of the digits from 1 to 5 is imposed.
There are 5 ways to place the digits 6, 7 ways to place the digit 7, 8 ways to place the digit 8 and 9 ways to place the digit 9.
We obtain 5*7*8*9 = 2520 numbers.
LINKS
CROSSREFS
Sequence in context: A053654 A240587 A323026 * A147647 A269119 A068249
KEYWORD
nonn,base,fini,full,less
AUTHOR
Michel Lagneau, Nov 22 2014
STATUS
approved