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Pentagonal number - Wikipedia, the free encyclopedia |
 | | A pentagonal number is a figurate number that extends the concept of triangular and square numbers to the pentagon, but, unlike the first two, the patterns involved in the construction of pentagonal numbers are not rotationally symmetrical. |
 | | 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, 176, 210, 247, 287, 330, 376, 425, 477, 532, 590, 651, 715, 782, 852, 925, 1001 (sequence A000326 in OEIS) |
 | | The nth pentagonal number is one third of the 3n-1th triangular number. |
| en.wikipedia.org /wiki/Pentagonal_number (316 words) |
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