The first thirteen palindromic triangular numbers

 
 
Here are the first thirteen palindromic triangular numbers:

   T_0 \; = \; 0
   T_1 \; = \; 1
   T_2 \; = \; 3
   T_3 \; = \; 6
  T_{10} \; = \; 55
  T_{11} \; = \; 66
  T_{18} \; = \; 171
  T_{34} \; = \; 595
  T_{36} \; = \; 666
  T_{77} \; = \; 3003
T_{109} \; = \; 5995
T_{132} \; = \; 8778
T_{173} \; = \; 15051
 

The sum of the indices is itself palindromic:

0+1+2+3+10+11+18+34+36+77+109+132+173=606

 
 
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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About benvitalis

math grad - Interest: Number theory
This entry was posted in Number Puzzles and tagged . Bookmark the permalink.

2 Responses to The first thirteen palindromic triangular numbers

  1. paul says:

    You could have also gone 1 more to T363 = 66066
    and 606 + 363 = 969.
    P.

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