OFFSET
1,1
COMMENTS
Also, a(n) is the smallest positive integer such that n^3 + a(n) is a square. - Bruno Berselli, Jan 29 2013
For n = m^2, a(n) = 2*m^3 + 1; e.g., a(1) = 2*1^3 + 1 = 3, a(4) = 2*2^3 + 1 = 17, a(9) = 2*3^3 + 1 = 55; otherwise a(n) < 2*n^(3/2) + 1. - Zak Seidov, Mar 24 2013
LINKS
Zak Seidov, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = floor(n^(3/2) + 1)^2 - n^3.
EXAMPLE
a(2) = floor(2^(3/2) + 1)^2 - 2^3 = 9 - 8 = 1.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Aug 02 2006
STATUS
approved