1,2

A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.

Table of n, a(n) for n=1..22.

Eric Weisstein's World of Mathematics, Hex Number.

Eric Weisstein's World of Mathematics, Scalene Triangle.

a(n) = A241223(n) - A241228(n).

Cf. A190312.

Sequence in context: A013587 A126159 A220992 * A268549 A071307 A195574

Adjacent sequences: A241224 A241225 A241226 * A241228 A241229 A241230

nonn,more

Martin Renner, Apr 17 2014

a(7) from Martin Renner, May 31 2014

a(8)-a(22) from Giovanni Resta, May 31 2014

approved