Square triangular number
In mathematics, a square triangular number (or triangular square number) is a number which is both a triangular number and a square number, in other words, the sum of all integers from to has a square root that is an integer. There are infinitely many square triangular numbers; the first few are:
0, 1, 36, 1225, 41616, 1413721, 48024900, 1631432881, 55420693056, 1882672131025 (sequence A001110 in the OEIS)
| N A001110 |
s2 = N A001109 |
t(t+1)/2 = N A001108 |
|---|---|---|
| 0 | 0 | 0 |
| 1 | 1 | 1 |
| 36 | 6 | 8 |
| 1225 | 35 | 49 |
| 41616 | 204 | 288 |
| 1413721 | 1189 | 1681 |
| 48024900 | 6930 | 9800 |