OFFSET
1,1
COMMENTS
A vector is a direction vector if its nonzero components have their GCD = 1.
EXAMPLE
The 4 directions towards points at squared distance 29 (i.e. for n=15) are (signed permutations of) [ 24,16,3 ],[ 24,12,11 ],[ 21,20,0 ],[ 21,16,12 ]
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Missing a(40)=480 inserted by Sean A. Irvine, Jul 28 2021
STATUS
approved