OFFSET
1,2
LINKS
D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic, arXiv:1107.1130 [math.NT], 2011. [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
EXAMPLE
The first 11 rows give the divisors of 1 through 11:
1 2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9
3 4 5 6 7 8 9
4 5 6 7 8 9
5 6 7 8 9
6 7 8 9
7 8 9
8 9
9
1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90
1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39 41 ... 99 (= all zeroless 1- and 2-digit numbers).
PROG
(PARI) A189506_row(n)={my(d=digits(n), m=vecmin(d), c=vector(#d, i, List()), K, t); for(L=1, #d, K=#d-L+1; forvec(v=vector(L, i, [max(m, i==1), 9]), L<=K&& listput(c[L], fromdigits(v))&&next; t=fromdigits(v); forstep(i=#c[K], 1, -1, A087062(c[K][i], t)==n||next; listput(c[L], t); break)); L>=K&&forstep(i=#c[K], 1, -1, t=c[K][i]; forstep(j=#c[L], 1, -1, A087062(c[L][j], t)==n&&next(2)); listpop(c[K], i))); Set(concat(c))} \\ M. F. Hasler, Nov 15 2018
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
N. J. A. Sloane, Apr 25 2011
EXTENSIONS
Minor edits by M. F. Hasler, Nov 15 2018
STATUS
approved