sn=na 1+n(n- 1)d/2=dn^2/2+(a 1-d/2)n

The general formula is: an = a1+(n-1) * D. The first term a 1= 1, and the tolerance d=2. The first n terms and formulas are: sn = a1* n+[n * (n-1) * d]/2 or Sn=[n*(a 1+an)]/2. Note: All the above n are positive integers.

Extended data:

Arithmetic progression's formula:

Tolerance d = (an-a 1) ÷ (n- 1) (where n is greater than or equal to 2 and n is a positive integer);

Number of items = (from the last item to the first item) ÷ tolerance+1;

The last item = the first item+(item number-1) × tolerance;

The sum of the first n terms Sn = the first term× n+terms (number of terms-1) tolerance/2;

The value of the nth term an = the first term+(number of terms-1) × tolerance;

The formula 2an+ 1 = an+an+2 in the arithmetic source sequence, where {an} is arithmetic progression;

Arithmetic progression's sum = (the first item+the last item) × the number of items ÷ 2;

An = am+(n-m) d, if an am is known, the formula related to d can be listed to solve an.