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A056535
Mapping from the ordering by sum to the ordering by product of the ordered pairs. Inverse permutation to A056534.
4
1, 2, 3, 4, 7, 5, 6, 12, 13, 8, 9, 18, 22, 19, 10, 11, 25, 32, 33, 26, 14, 15, 31, 43, 48, 44, 34, 16, 17, 39, 55, 63, 64, 56, 40, 20, 21, 47, 68, 80, 86, 81, 69, 49, 23, 24, 54, 79, 98, 107, 108, 99, 82, 57, 27, 28, 62, 93, 116, 129, 136, 130, 117, 94, 65, 29, 30, 72, 106
OFFSET
1,2
COMMENTS
The last term of the each row r of the triangle is the first term of that row + (tau(r)-1).
As an array, T(n,k) is the index of the k-th term of A027750 whose value is n. - Michel Marcus, Oct 15 2015
FORMULA
[seq(nthmember(j, A056534), j=1..105)];
EXAMPLE
As a triangle, sequence begins:
1;
2, 3;
4, 7, 5;
6, 12, 13, 8;
9, 18, 22, 19, 10;
...
As an array, sequence begins:
1, 2, 4, 6, 9, 11, 15, ...
3, 7, 12, 18, 25, 31, 39, ...
5, 13, 22, 32, 43, 55, 68, ...
8, 19, 33, 48, 63, 80, 98, ...
10, 26, 44, 64, 86, 107, 129, ...
...
MAPLE
Maple procedure nthmember given in A054426.
MATHEMATICA
a[n_] := If[p = Position[A056534, n]; p != {}, p[[1, 1]], 0]; (* Jean-François Alcover, Aug 20 2013 *)
CROSSREFS
A056535[A000217[i]] = A056535[A000217[i-1]+1]+A000005[i]-1, for all i >= 1.
Left edge: A054519, Right edge: A006218.
Sequence in context: A072658 A099864 A292956 * A026237 A308301 A373853
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Jun 20 2000
STATUS
approved