Pascal’s triangle is a triangle that gives binomial coefficients of different polynomials. Each row in the triangle tells the degree of the expression. Starting with row 0, row 1, row 2 etc we can build the triangle to say from the previous row. The first number in row n is the sum of the first and next number in row n-1, and does goes on. But now in this post, I am trying to come up with a pattern row formula and here is each step in my formula making!
We start with row 0 and row 1 as given.
Let’s say the row number is n. So row 0 means n=0.
Let’s say the number of terms in a row is t, so first row where n=0, t=1.
n=1, t=2
n=2, t=3
n=3, t=4
Let’s say the coefficients in each row is ct.
so row 0, t=1 so, c1=1
Row 1, t=2, c1=1, c2=1
Row 2, t=3, c1=1, c2=2, c3=1
Row 3, t=4, c1=1, c2=3, c3=3, c4=1
Row 4, t=5, c1=1, c2=4, c3=6, c4=4, c5=1
So, the pattern is as follows:
For a given row n,
The number of terms t=n+1
The number of coefficients is number of terms, t.
The main part is calculating the value of the coefficients.
The first and last coefficients are always 1.
C1 = ct
Second from left = second from right or c2=c(t-1)
Third from left = third from right or c3=c(t-2) and so on
C(1+x) =C(t-x) – increment x until 1+x >= t-x
Now, calculating other coefficients in the row.
Another pattern is that c2=n=c(t-2) ;
so row n=2, c2=2
so row n=3, c2=3=c3
Now really didn’t find the pattern for terms above row n=3.
My formula can build the Pascal’s triangle up to row 3.
For row n= 0 to 3,
t = n+1
C(1+x) = C(t-x) until 1+x >= t-x
Repeat until n=3.
I also think really there is a easy formula for this to calculate the complete triangle.
One thought on “119: Pascal‘s Triangle !”
Cool. Try this:
for each row n: for r =0 to n: coeff = n! /(r! * (n-r)!)
where ! = factorial. Start at row n=0