A309914 Distance from n to closest triangular number that is different from n.

1, 1, 1, 2, 1, 1, 3, 1, 2, 1, 4, 1, 2, 2, 1, 5, 1, 2, 3, 2, 1, 6, 1, 2, 3, 3, 2, 1, 7, 1, 2, 3, 4, 3, 2, 1, 8, 1, 2, 3, 4, 4, 3, 2, 1, 9, 1, 2, 3, 4, 5, 4, 3, 2, 1, 10, 1, 2, 3, 4, 5, 5, 4, 3, 2, 1, 11, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 12, 1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1, 13, 1, 2, 3, 4, 5, 6, 7, 6, 5

Offset: 0

Author

Ilya Gutkovskiy, Aug 22 2019

Keywords

• nonn

Links

• Index entries for sequences related to distance to nearest element of some set

Crossrefs

Cf. A000217, A053188, A053616, A066635.

Programs

Mathematica

a[n_] := Module[{k = 1}, While[! IntegerQ[Sqrt[8 (n + k) + 1]] && ! IntegerQ[Sqrt[8 (n - k) + 1]], k++]; k]; Table[a[n], {n, 0, 100}]