OFFSET
1,2
COMMENTS
Since the only numbers invariant under this iteration are 1 and 9, n is contained in this sequence iff the sum of digits of n^2 is 1 or 9.
EXAMPLE
6 -> 3+6 = 9 -> 8+1 = 9 thus 9 is the only element of the iterative cycle of 6. 12 -> 1+4+4 = 9 -> 8+1 = 9 ...
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Asher Auel, May 17 2001
STATUS
approved