OFFSET
0,6
LINKS
Alois P. Heinz, Antidiagonals n = 0..31, flattened
EXAMPLE
Square array A(n,k) begins:
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
2, 1, 0, 0, 0, 0, 0, 0, 0, 0, ...
3, 2, 1, 0, 0, 0, 0, 0, 0, 0, ...
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, ...
5, 3, 2, 1, 0, 0, 0, 0, 0, 0, ...
6, 7, 4, 4, 4, 4, 4, 4, 4, 4, ...
7, 4, 4, 4, 4, 4, 4, 4, 4, 4, ...
8, 12, 20, 32, 80, 208, 512, 2304, 12288, 81920, ...
9, 12, 20, 32, 80, 208, 512, 2304, 12288, 81920, ...
MAPLE
with(numtheory):
d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end:
seq(seq(A(n, h-n), n=0..h), h=0..14);
MATHEMATICA
d[n_] := n*Total[Last[#]*PrimePi[First[#]]/First[#]& /@ FactorInteger[n]]; d[0] = 0;
A[n_, k_] := A[n, k] = If[k == 0, n, d[A[n, k-1]]];
Table[Table[A[n, h-n], {n, 0, h}], {h, 0, 14}] // Flatten (* Jean-François Alcover, Apr 24 2016, adapted from Maple *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Jun 12 2015
STATUS
approved