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%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
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