678030

Appears in sequences

• Triangular numbers whose digit reversal is also a triangular number.at n=30A061455
• Nonpalindromic triangular numbers whose digit reversal is also a triangular number (possibly with fewer digits).at n=15A069673
• a(n) = larger member of n-th pair of distinct, positive, triangular numbers whose sum and difference are also triangular numbers.at n=17A185128