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pentagonal number sequence

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This commit is contained in:
Stefan Harmuth 2022-08-07 18:45:33 +02:00
parent 1b4ef0276b
commit 2ac37ad567
1 changed files with 8 additions and 0 deletions
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8
tools/int_seq.py
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@ -28,3 +28,11 @@ def triangular(n: int) -> int:
0, 1, 3, 6, 10, 15, ...
"""
return n * (n + 1) // 2
def pentagonal(n: int) -> int:
"""
A pentagonal number is a figurate number that extends the concept of triangular and square numbers to the pentagon
0, 1, 5, 12, 22, 35, ...
"""
return ((3 * n * n) - n) / 2