Fill in the blanks

Question

for(i=0;i<5;i++)
{
for(j=0;j<=i;j++)
{
printf("%d",______);
}
printf("\n");
}

output
5
4 8
3 6 9
2 4 6 8
1 2 3 4 5

Answer 1

((j+1) + (4-i) * (j+1))