OFFSET
0,2
COMMENTS
Also the least common multiple of all rows of triangle A069011 up to the n-th row.
lcm(0) is taken to be 1, which follows from 0! = 1.
FORMULA
a(n) = lcm({ x,y:N | 0 <= x <= y <= n; x^2+y^2 })
EXAMPLE
a(3) = lcm(0^2+0^2; 0^2+1^2, 1^2+1^2; 0^2+2^2, 1^2+2^2, 2^2+2^2; 0^2+3^2, 1^2+3^2, 2^2+3^2, 3^2+3^2) = lcm(0; 1, 2; 4, 5, 8; 9, 10, 13, 18) = 4680.
PROG
(PARI) a(n) = {mcl = 1; for (x = 0, n, for (y = 0, n, if (v = x^2+y^2, mcl = lcm(mcl, v)); ); ); mcl; } \\ Michel Marcus, Sep 03 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Carl R. White, Jul 15 2009
STATUS
approved