Centered Hexagonal Number

As stated on the On-Line Encyclopedia of Integer Sequences:

The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors.

A centered hexagonal number is a centered figurate number that represents a hexagon with a dot in the center and all other dots surrounding the center dot in a hexagonal lattice.

At the end of that web page the following illustration is shown:

Illustration of initial terms:
.
.                                 o o o o
.                   o o o        o o o o o
.         o o      o o o o      o o o o o o
.   o    o o o    o o o o o    o o o o o o o
.         o o      o o o o      o o o o o o
.                   o o o        o o o o o
.                                 o o o o
.
.   1      7          19             37
.

Write a function that takes an integer n and returns "Invalid" if n is not a centered hexagonal number or its illustration as a multiline rectangular string otherwise.

Examples

hexLattice(1) ➞ " o "
// o

hexLattice(7) ➞ "  o o  \n o o o \n  o o  "
//  o o
// o o o
//  o o

hexLattice(19) ➞ "   o o o   \n  o o o o  \n o o o o o \n  o o o o  \n   o o o   "
//   o o o
//  o o o o
// o o o o o
//  o o o o
//   o o o

hexLattice(21) ➞ "Invalid"

Notes

N/A