Miscellany

#include<stdio.h>
#include<stdlib.h>

typedef struct number_node {
        char digit;
        struct number_node *next;
} number;

int main() {
        number *head;
        int len;
        int tobase = 7;
        int i;

        head = (number*)malloc(sizeof(number));
        head->digit = 1;
        head->next = NULL;


        for(i=1;i<10000;i++) {
                int remainder = 0;
                int n = 0;
                char three = 0;
                int row = 0;
                number *current = head;

                do {
                        int temp = current->digit * 2 + remainder;
                        current->digit = temp % tobase;
                        remainder = (temp - current->digit) / tobase;
                        if(current->digit == 0) row++;
                        else row=0;
                        if(row == 3) three = 1;
                        n++;
                        if(current->next) current = current->next;
                        else if(remainder) {
                                current->next = malloc(sizeof(number));
                                current = current->next;
                                current->digit = 0;
                                current->next = NULL;
                                len++;
                        }
                        else current = NULL;
                } while(current);
                if(three)
                        printf("%d\n",i);
        }
        return 0;
}