[seqfan] Re: Summer sequence boot camp : adding digits to the right... and more

Erich Friedman efriedma at stetson.edu
Mon Aug 8 15:19:43 CEST 2011

> ***Question (1):
>   What are the first 100 integers with no predecessors?

0, and the three digit numbers where the middle digit is at least as large as the other two, are the first ones.

> ***Question (2)
>   What are the first 100 "looping integers"?

only 15 cycles (36 looping integers) are known: 

99(a+1) --> 181a --> 99(a+1)   [where 0≤a≤8]

3333(a+1) --> 666(a+4) --> 12121a -->3333(a+1)   [where 0≤a≤5]

see  http://www2.stetson.edu/~efriedma/mathmagic/0200.html  for more info.


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