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

1,2

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.

Links

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

Example

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;

Crossrefs

Cf. A069800.

Sequence in context: A109302 A081480 A070841 * A019074 A019075 A006709

Adjacent sequences: A069798 A069799 A069800 * A069802 A069803 A069804

Keyword

nonn,tabf,base,look

Author

Amarnath Murthy, Apr 13 2002

Extensions

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

Status

approved