OFFSET
1,1
REFERENCES
H. E. Huntley, The Divine Proportion, A Study in Mathematical Beauty. New York: Dover, 1970. See Chapter 13, Spira Mirabilis, especially Fig. 13-5, page 173.
FORMULA
To begin prime spiral, plot (2, 0), (0, 2). Square of hypotenuse is c^2 = a^2 + b^2, or 8 = 4 + 4, so a(1) = 8.
a(n) = A069484(n-1), n >= 2. - Mamuka Jibladze, Mar 24 2017
EXAMPLE
a(2) = 13 because c^2 = a^2 + b^2 = 4 + 9 = 13.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved