1,3

Reinhard Zumkeller conjectures (at A102730) that this sequence is finite. I conjecture the contrary, that a(n) exists for every n. Further, I expect a(n) << n^n. [Charles R Greathouse IV, Aug 21 2011]

Table of n, a(n) for n=1..12.

a(6) = 5: A102730(5) = #{0,1,2,3,4,5} = 6;

a(7) = 8: A102730(8) = #{0,1,2,3,4,7,8} = 7;

a(8) = 23: A102730(23) = #{0,1,2,3,4,5,6,23} = 8;

a(9) = 117: A102730(117) = #{0,1,2,3,4,5,6,7,117} = 9;

a(10) = 155: A102730(155) = #{0,1,2,3,4,5,6,7,8,155} = 10.

Sequence in context: A057657 A116657 A079383 * A105950 A227778 A166276

Adjacent sequences: A103667 A103668 A103669 * A103671 A103672 A103673

nonn,hard

Reinhard Zumkeller, Feb 12 2005

a(11) and a(12) from D. S. McNeil, Aug 21 2011

approved