[Solved] I have to print a series using for loop

The following block should generate the series as you described it.

int numberOfLines = 4;
int numberOfDigitsPerLine = 5;

for (int i=1; i<numberOfLines+1; i++){
    for(int j=1; j<=numberOfDigitsPerLine; j++) {
        if(j>=i) {
            System.out.print(j);
        } else {
            System.out.print(i);
        }
    }
    System.out.println();
}

Change numberOfLines and numberOfDigitsPerLine as necessary.

Elaboration:

First you must analyze the series, by the looks of it the first number starts with 1 and goes onward for 5 digits, the second line goes along 5 digits as well up to 5 as previously but it replaces the first digit with 2.

Moving down the numbers we can see a pattern of which the N-th number will have N amount of N digits followed by consecutive digits up to the number 5.

So in my code above I chose max N to be 4 as you described it, and the numbers go up to 5, these are represented by the variables numberOfLines and numberOfDigitsPerLine respectively.

The block itself checks what is N at that point (in my block it is represented by i) and then proceeds to go towards the max number 5, this is done within the j for loop. If j is larger or equal to N then we print j, otherwise we haven’t finished printing all of the N’s yet so we print N instead.