A374369 Triangle T(n, k), n > 0, k = 0..n-1, read by rows; T(n, k) is the least m such that n and k differ modulo m.

2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 2, 4, 2, 3, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 2, 3, 2, 4, 2, 3, 2, 3, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2

Offset

1,1

Links

Table of n, a(n) for n=1..91.

Formula

T(n, k) = A007978(n-k).

Example

Triangle T(n, k) begins:
  n   n-th row
  --  ----------------------------------
   1  2
   2  3, 2
   3  2, 3, 2
   4  3, 2, 3, 2
   5  2, 3, 2, 3, 2
   6  4, 2, 3, 2, 3, 2
   7  2, 4, 2, 3, 2, 3, 2
   8  3, 2, 4, 2, 3, 2, 3, 2
   9  2, 3, 2, 4, 2, 3, 2, 3, 2
  10  3, 2, 3, 2, 4, 2, 3, 2, 3, 2
  11  2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2
  12  5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2

Mathematica

T[n_, k_]:=Module[{m=2}, While[Mod[n, m]==Mod[k, m], m++]; m]; Table[T[n, k], {n, 13}, {k, 0, n-1}]//Flatten (* Stefano Spezia, Jul 12 2024 *)

Prog

(PARI) T(n, k) = { for (m = 2, oo, if ((n%m) != (k%m), return (m); ); ); }

Crossrefs

Cf. A007978, A374381, A374383.

Sequence in context: A333853 A182006 A085239 * A242872 A329362 A372971

Adjacent sequences: A374366 A374367 A374368 * A374370 A374371 A374372

Keyword

nonn,easy,tabl

Author

Rémy Sigrist, Jul 06 2024

Status

approved