Deceptive numbers: Difference between revisions

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@@ Line 171: / Line 171: @@
 /* wheel to skip multiples of 2, 3, and 5 */
-w[0] = 2
+w[0] = 4
-w[1] = 4
+w[1] = 2
-w[2] = 2
+w[2] = 4
-w[3] = 4
+w[3] = 2
-w[4] = 6
+w[4] = 4
-w[5] = 2
+w[5] = 6
-w[6] = 6
+w[6] = 2
-w[7] = 4
+w[7] = 6
-for (n = 11; c != 10; i = (i + 1) % 8) {
+for (n = p[0]; c != 10; i = (i + 1) % 8) {
-    if (d(n) == 1) {
+    if (d(n += w[i]) == 1) {
         n
         c += 1
     }
-    n += w[i]
 }</syntaxhighlight>
 {{out}}
@@ Line 1,231: / Line 1,230: @@
 =={{header|UNIX Shell}}==
+Works with [[POSIX]]-compatible shells.
 <syntaxhighlight lang="sh">is () {
     return "$((!($1)))"
 }
-modpow () {
+fermat_test () {
-    set -- 1 "$@"
+    set -- 1 "$1" "$(($2 - 1))" "$2"
-    while is "$3 != 0"
+    while is "$3 > 0"
     do
         set -- "$(($1 * (($2 ^ 1) * ($3 & 1) ^ 1) % $4))" "$(($2 * $2 % $4))" "$(($3 >> 1))" "$4"
     done
-    echo "$1"
+    return "$(($1 != 1))"
 }
+set -- 7
-c=0 n=7
+c=0 n=$1
-set -- "$n"
 while :
 do
     for w in 4 2 4 2 4 6 2 6
     do
-        n=$((n + w))
+        fermat_test 10 "$((n += w))" && for p
-        is "$(modpow 10 "$((n - 1))" "$n") == 1" && for p
         do
             is 'p * p > n' && {