OFFSET
1,2
COMMENTS
LINKS
G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
FORMULA
EXAMPLE
First few rows of the triangle =
1;
2, 1;
3, 1, 3;
4, 2, 3, 7;
5, 2, 3, 7, 16;
6, 3, 6, 7, 16, 33;
7, 3, 6, 7, 16, 33 71;
8, 4, 6, 14, 16, 33, 71, 143;
9, 4, 9, 14, 16, 33, 71, 143, 295;
10, 5, 9, 14, 32, 33, 71, 143, 295, 594;
11, 5, 9, 14, 32, 33, 71, 143, 295, 594, 1206;
12, 6, 12, 21, 32, 66, 71, 143, 295, 594, 1206, 2413;
...
Example: row 4 = (4, 2, 3, 7) = (4, 2, 1, 1) * (1, 1, 3, 7).
MATHEMATICA
a[1] = 1; a[n_] := a[n] = Sum[Sum[a[d], {d, Divisors[k]}], {k, 1, n -1}];
Table[Floor[n/k]* a[k], {n, 1, 5}, {k, 1, n}]//Flatten (* G. C. Greubel, Dec 18 2016 *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson & Mats Granvik, Jul 30 2009
STATUS
approved