vector(10, k, stirling(11,k))
vector(11, k, stirling(12,k))
vector(10, k, stirling(11,k, 2))
vector(11, k, stirling(12,k, 2))
v = vector(5!,i,numtoperm(5, i-1))
if(vecsort(v,lex)!=v,error("numtoperm"));
vector(#v, i, permtonum(v[i]))
vector(#v, i, permtonum(Vecsmall(v[i])))
stirling(100,0)
iferr(permtonum([1,3,0]), E, Vec(E))
permtonum(1)
permtonum([])
numtoperm(0,0)
