A322426 - OEIS

%I #12 Mar 15 2019 18:51:44

%S 1,2,1,1,2,1,1,3,2,1,1,1,3,2,1,2,2,4,3,2,1,1,1,1,4,3,2,1,1,2,2,5,4,3,

%T 2,1,2,1,3,1,5,4,3,2,1,1,2,1,2,6,5,4,3,2,1,1,1,2,3,1,6,5,4,3,2,1,1,2,

%U 3,4,2,7,6,5,4,3,2,1,2,3,1,1,3,1,7,6,5

%N Array read by downwards antidiagonals: A(n, k) is the k-th term of a "Look to the left" sequence starting with 1,2,...,n  (see A293630).

%H Iain Fox, <a href="/A322426/b322426.txt">Antidiagonals n = 1..141 of array, flattened</a>

%F If k <= n, A(n, k) = k.

%e | n\k |  1   2   3   4   5   6   7   8   9  10  11  12  13  ...

%e |-----|-----------------------------------------------------------

%e |  2  |  1,  2,  1,  1,  1,  2,  1,  1,  2,  1,  1,  1,  2, ...

%e |  3  |  1,  2,  3,  1,  2,  1,  2,  1,  2,  1,  2,  3,  1, ...

%e |  4  |  1,  2,  3,  4,  1,  2,  3,  1,  2,  3,  1,  2,  3, ...

%e |  5  |  1,  2,  3,  4,  5,  1,  2,  3,  4,  1,  2,  3,  4, ...

%e |  6  |  1,  2,  3,  4,  5,  6,  1,  2,  3,  4,  5,  1,  2, ...

%e |  7  |  1,  2,  3,  4,  5,  6,  7,  1,  2,  3,  4,  5,  6, ...

%e |  8  |  1,  2,  3,  4,  5,  6,  7,  8,  1,  2,  3,  4,  5, ...

%e | ... |

%o (PARI) row(n, k) = my(v=vector(n, i, i), w); while(#v<k, w=vector(#v-1, i, v[i]); for(y=1, v[#v], v=concat(v, w))); vector(k, i, v[i])

%o first(n, k) = my(v, m=matrix(0, k)); for(x=1, n, v=row(x+1, k); m=concat(m, v)); m

%Y n-th row: A293630 (n=2), A322423 (n=3), A322424 (n=4), A322425 (n=5).

%K nonn,tabl,look

%O 2,2

%A _Iain Fox_, Dec 07 2018