A069801 Triangular array in which the n-th row consists of numbers with digit product n arranged in increasing numerical order; row consists of 0 if no such numbers exist.

1, 2, 3, 4, 22, 5, 6, 23, 32, 7, 8, 24, 42, 222, 9, 33, 25, 52, 0, 26, 34, 43, 62, 223, 232, 322, 0, 27, 72, 35, 53, 28, 44, 82, 224, 242, 422, 2222, 0, 29, 36, 63, 92, 233, 323, 332, 0, 45, 54, 225, 252, 522, 37, 73, 0, 0, 38, 46, 64, 83, 226, 234, 243, 262

Offset: 1

Author

Amarnath Murthy, Apr 13 2002

Keywords

• nonn
• tabf
• base
• look

Comments

1 is not allowed as a digit, except in the first row.

If n has any prime factor other than 2,3,5 or 7 then a(n) = 0.

Examples

			Triangular array begins:
1;
2;
3;
4,  22;
5;
6,  23, 32;
7;
8,  24, 42, 222;
9,  33;
25, 52;
0;
26, 34, 43,  62, 223, 232, 322;
		

Links

• Alois P. Heinz, Rows n = 1..1000, flattened

Crossrefs

Cf. A069800.

Extensions

Corrected and extended by Alois P. Heinz, Sep 24 2013