A288351 Number of strings of n digits from 1...9 such that no formula using the single digits in the given order exists that evaluates to 0.

9, 72, 455, 1500, 1014, 181, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 1

Author

Hugo Pfoertner, Jun 08 2017

Keywords

• nonn

Comments

For definitions and comments see A288350.

It is conjectured that a(n)=0 for n>=8.

The conjecture is true, as shown in the corresponding comment in A288350. - Hugo Pfoertner, Jun 09 2017

Examples

			a(1)=9 because 1...9 /=0. a(2)=72, because only the 9 numbers 11, 22, ..., 99 of the 81 two-digit strings can represent 0.
		

Crossrefs

Cf. A288350, A288352, A288353, A288354, A288355, A288356.