Math - 3N+1

Longest non self loop interaction

• 2022-04-13: 860 @ 295,147,905,179,352,826,087 [0.295 E21]

Code from 1

#!/bin/bash

i=1

while true; do

  c=1

  n=$i

  printf "$n"

  while [[ $n != "1" ]]; do

    # bc has no limit for the number of digits (as much as memory can hold)

    case $n in

    *0 | *2 | *4 | *6 | *8) n=$( echo "$n / 2"|bc) ;;

    *) n=$( echo "$n * 3 + 1"|bc) ;;

    esac

    printf " -> $n"

    c=$((c+1))

  done

  echo " [$c]"

  # maybe use bc ....

  i=$((i+1))

done

Code from 2^68

#!/bin/bash

export BC_LINE_LENGTH=0

i=295147905179352825856

while true; do

  c=1

  n=$i

  printf "$n"

  while [[ $n != "1" ]]; do

    case $n in

    *0 | *2 | *4 | *6 | *8) n=$( echo "$n / 2"|bc) ;;

    *)         n=$( echo "$n * 3 + 1"|bc)

    esac

    printf " -> $n"

    c=$((c+1))

  done

  echo " [$c]"

  i=$( echo "$i+1"|bc)

done