OFFSET
1,1
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000 (first 150 terms from Colin Barker)
EXAMPLE
144 is in the sequence because there are 5 solutions to x^2 - y^2 = 144, namely (x,y) = (12,0), (13,5), (15,9), (20,16), (37,35).
MATHEMATICA
nn = 4000;
t = Table[0, {nn}];
Do[n = x^2 - y^2; If[n <= nn, t[[n]]++], {x, nn}, {y, 0, x - 1}];
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Colin Barker, Apr 22 2015
STATUS
approved