A390458 Minimum site perimeter of a polyiamond with n cells.

3, 4, 5, 6, 6, 6, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 20, 21, 21

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Wikipedia, Polyiamond.

Formula

a(n) = min({k; A069813(k)>=n}).

a(n) = min({A067628(k); k>=n}).

a(n) = ceiling(sqrt(6*n+2)) - [6*n is a perfect square].

Mathematica

A390458[n_] := Ceiling[Sqrt[6*n + 2]] - Boole[IntegerQ[Sqrt[6*n]]];
Array[A390458, 100] (* Paolo Xausa, Nov 10 2025 *)

Crossrefs

Cf. A067628, A069813, A182619, A261491.

Sequence in context: A162552 A133575 A230113 * A396726 A364528 A217031

Adjacent sequences: A390455 A390456 A390457 * A390459 A390460 A390461

Keyword

nonn

Author

Pontus von Brömssen, Nov 06 2025

Status

approved