func main() {
n, num := 1, uint32(2*3*5*7)
for n != 4 {
num++
if len(mathutil.FactorInt(num)) == 4 {
n++
} else {
n = 0
}
}
fmt.Println(num - 4 + 1)
}
func main() {
pp := mathutil.PrimorialProductsUint32(0, math.MaxUint32, 32)
sort.Sort(sortutil.Uint32Slice(pp))
var bestN, bestD uint32 = 1, 1
order, checks := 0, 0
var ixDirty uint32
m := make([]byte, math.MaxUint32>>3)
for _, n := range pp {
for i := range m[:ixDirty+1] {
m[i] = 0
}
ixDirty = 0
checks++
limit0 := mathutil.QScaleUint32(n, bestN, bestD)
if limit0 > math.MaxUint32 {
panic(0)
}
limit := uint32(limit0)
n64 := uint64(n)
hi := n64 >> 1
hits := uint32(0)
check := true
fmt.Printf("\r%10d %d/%d", n, checks, len(pp))
t0 := time.Now()
for i := uint64(0); i < hi; i++ {
sq := uint32(i * i % n64)
ix := sq >> 3
msk := byte(1 << (sq & 7))
if m[ix]&msk == 0 {
hits++
if hits >= limit {
check = false
break
}
}
m[ix] |= msk
if ix > ixDirty {
ixDirty = ix
}
}
adjPrime := ".." // Composite before
if mathutil.IsPrime(n - 1) {
adjPrime = "P." // Prime before
}
switch mathutil.IsPrime(n + 1) {
case true:
adjPrime += "P" // Prime after
case false:
adjPrime += "." // Composite after
}
if check && mathutil.QCmpUint32(hits, n, bestN, bestD) < 0 {
order++
d := time.Since(t0)
bestN, bestD = hits, n
q := float64(hits) / float64(n)
fmt.Printf(
"\r%2s #%03d %d %d %.2f %.2E %s %s %v\n",
adjPrime, order, n, hits,
1/q, q, d, time.Now().Format("15:04:05"), mathutil.FactorInt(n),
)
}
}
}