document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1150892>Question 1150892</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove by induction<BR>\n" );
document.write( "n*1 + (n-1)*2 + (n-2)*3 + ... + 3*(n-2) + 2*(n-1) + 1*n = n(n+1)(n+2)/6 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #772450 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=772450\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "See the links\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "https://www.physicsforums.com/threads/prove-that-n-1-n-1-2-n-2-3-3-n-2-2-n-1-1-n-n-n-1-n-2-6-by.514678/\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "http://mathforum.org/library/drmath/view/56920.html\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );