1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50+51+52+53+54+55+56+57+58+59+60+61+62+63

My Christmas ecard for 2016, a triangular number year ...  May your joy add up each day:

Merry Christmas!  Frohe Weihnachten!  There will not be another triangular number year for 64 years.