OFFSET
1,2
COMMENTS
Like A171785 but without the constraint a(n) > a(n-1).
Among the first 1000 terms, a(n) = n for n = 1, 2, 3, 15, 170, 577, 759, and the numbers not yet found are 149, 298, 347, 401, 447, 454, 457, 467, 487, 509, etc.
Is this sequence a rearrangement of the natural numbers?
LINKS
Paolo P. Lava, Table of n, a(n) for n = 1..1000
EXAMPLE
a(1) = 1;
a(2) = 2 -> 12 /2 = 6;
a(3) = 3 -> 123 / 3 = 41;
Then we cannot use 4 as the next term because 1234 / 4 = 617 / 2.
a(4) = 5 -> 1235 / 5 = 247;
Again, 4, 6, 7, 8 and 9 cannot be used as the next term.
a(5) = 10 -> 123510 / 10 = 12351;
a(6) = 4 -> 1235104 / 4 = 308776;
a(7) = 8 -> 12351048 / 8 = 1543881; etc.
MAPLE
with(numtheory); P:=proc(q) local a, b, k, n; a:=0; b:={};
for k from 1 to q do for n from 1 to q do if nops({n} intersect b)<1
then if type((a*10^(1+ilog10(n))+n)/n, integer)
then a:=a*10^(1+ilog10(n))+n; b:= b union {n}; print(n); break;
fi; fi; od; od; end: P(10^5);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava, Nov 27 2014
STATUS
approved