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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. 2
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 (list; graph; refs; listen; history; text; internal format)
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
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
KEYWORD
nonn,tabf,base,look
AUTHOR
Amarnath Murthy, Apr 13 2002
EXTENSIONS
Corrected and extended by Alois P. Heinz, Sep 24 2013
STATUS
approved

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Last modified March 4 13:15 EST 2024. Contains 370532 sequences. (Running on oeis4.)