login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A353109 Array read by antidiagonals: A(n, k) is the digital root of n*k with n >= 0 and k >= 0. 6
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, 3, 3, 1, 6, 0, 0, 7, 3, 6, 7, 6, 3, 7, 0, 0, 8, 5, 9, 2, 2, 9, 5, 8, 0, 0, 9, 7, 3, 6, 7, 6, 3, 7, 9, 0, 0, 1, 9, 6, 1, 3, 3, 1, 6, 9, 1, 0, 0, 2, 2, 9, 5, 8, 9, 8, 5, 9, 2, 2, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,8
LINKS
FORMULA
A(n, k) = A010888(A004247(n, k)).
A(n, k) = A010888(A003991(n, k)) for n*k > 0.
EXAMPLE
The array begins:
0, 0, 0, 0, 0, 0, 0, 0, ...
0, 1, 2, 3, 4, 5, 6, 7, ...
0, 2, 4, 6, 8, 1, 3, 5, ...
0, 3, 6, 9, 3, 6, 9, 3, ...
0, 4, 8, 3, 7, 2, 6, 1, ...
0, 5, 1, 6, 2, 7, 3, 8, ...
0, 6, 3, 9, 6, 3, 9, 6, ...
0, 7, 5, 3, 1, 8, 6, 4, ...
...
MATHEMATICA
A[i_, j_]:=If[i*j==0, 0, 1+Mod[i*j-1, 9]]; Flatten[Table[A[n-k, k], {n, 0, 12}, {k, 0, n}]]
PROG
(PARI) T(n, k) = if (n && k, (n*k-1)%9+1, 0); \\ Michel Marcus, May 12 2022
CROSSREFS
Cf. A003991, A004247, A010888, A056992 (diagonal), A073636, A139413, A180592, A180593, A180594, A180595, A180596, A180597, A180598, A180599, A303296, A336225, A353128 (antidiagonal sums), A353933, A353974 (partial sum of the main diagonal).
Sequence in context: A048720 A067138 A059692 * A336225 A004247 A271916
KEYWORD
nonn,tabl,base,easy
AUTHOR
Stefano Spezia, Apr 24 2022
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)