RSA GAME OVER (part II)

a^2+na=221
,
{a^2 +2[[(a-1)/2]^2-1]-[(a-2)^2+2[[(a-2-1)/2]^2-1]]-34}/6=k
,
{(k+1)^2 +2[[((k+1)-1)/2]^2-1]-[((k+1)-2)^2+2*[[((k+1)-2-1)/2]^2-1]]-34}/6=0