4thheptagonalnumber

<-- Enter heptagonal number statement
  

Calculate heptagonal number 4

The formula for heptagonal number n is as follows
Hn  =  n(5n - 3)
  2

Given n = 4, we have:
H4  =  4(5(4) - 3)
  2

H4  =  4(20 - 3)
  2

H4  =  4(17)
  2

H4  =  68
  2

H4 = 34