A391365 Array read by antidiagonals: A(n,k) = reverse(n*k) = A004086(n*k).

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 4, 3, 0, 0, 4, 6, 6, 4, 0, 0, 5, 8, 9, 8, 5, 0, 0, 6, 1, 21, 21, 1, 6, 0, 0, 7, 21, 51, 61, 51, 21, 7, 0, 0, 8, 41, 81, 2, 2, 81, 41, 8, 0, 0, 9, 61, 12, 42, 52, 42, 12, 61, 9, 0, 0, 1, 81, 42, 82, 3, 3, 82, 42, 81, 1, 0, 0, 11, 2, 72, 23, 53, 63, 53, 23, 72, 2, 11, 0

Offset

0,8

Links

Stefano Spezia, Table of n, a(n) for n = 0..11324 (first 150 antidiagonals of the array)

Example

The array begins as:
  0, 0,  0,  0,  0,  0,  0,  0, ...
  0, 1,  2,  3,  4,  5,  6,  7, ...
  0, 2,  4,  6,  8,  1, 21, 41, ...
  0, 3,  6,  9, 21, 51, 81, 12, ...
  0, 4,  8, 21, 61,  2, 42, 82, ...
  0, 5,  1, 51,  2, 52,  3, 53, ...
  0, 6, 21, 81, 42,  3, 63, 24, ...
  0, 7, 41, 12, 82, 53, 24, 94, ...
  0, 8, 61, 42, 23,  4, 84, 65, ...
  ...

Mathematica

A[n_, k_]:=IntegerReverse[n*k]; Table[A[n-k, k], {n, 0, 12}, {k, 0, n}]//Flatten

Crossrefs

Cf. A003991, A059692, A110749, A336225, A353109.

Rows or columns give: A004086, A004093, A248423.

A002942 gives the main diagonal.

Sequence in context: A059692 A353109 A336225 * A004247 A271916 A327031

Adjacent sequences: A391362 A391363 A391364 * A391366 A391367 A391368

Keyword

nonn,base,look,tabl

Author

Stefano Spezia, Feb 15 2026

Status

approved