i+2i²+3i³+4i^4=i-2-3i+4=2-2i5i^5+6i^6+7i^7+8i^8=5i-6-7i+8=2-2i9i^9+10i^10+11i^11+12i^12=9i-10-11i+12=2-2i..2001i^2001+2002i^2002+2003i^2003+2004i^2004=2001i-2002-2003i+2004=2-2i2005i^2005+20...