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centered square n.  and  pentagonal n.

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(max 15 digits)

First numbers that belong to both sets:

1, 5, 145, 925, 28085, 179401, 5448301, 34802825, 1056942265, 6751568605, 205041351065, 1309769506501, 39776965164301, 254088532692545.