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

0,4

Links

Table of n, a(n) for n=0..100.

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

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}]

Crossrefs

Cf. A000217, A053188, A053616, A066635.

Sequence in context: A128221 A327856 A175488 * A364911 A115758 A228351

Adjacent sequences: A309911 A309912 A309913 * A309915 A309916 A309917

Keyword

nonn

Author

Ilya Gutkovskiy, Aug 22 2019

Status

approved