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145 (number)

Field	Value
number	145
divisor	1, 5, 29, 145

145 (one hundred [and] forty-five) is the natural number following 144 and preceding 146.

In mathematics

Although composite, 145 is a Fermat pseudoprime in sixteen bases with b
The Mertens function returns 0.
145 is a pentagonal number and a centered square number.
145 = 12^2 + 1^2 = 8^2 + 9^2. 145 is the fourth number that is the sum of two different pairs of squares. Also, 145 is the result of 34 + 43, making it a Leyland number.
145 = 1! + 4! + 5!, making it a factorion. The only other numbers that have this property are 1, 2 and 40585.
145=5^2+5!=11^2+4!=12^2+1!, making 145 the smallest number that can be written as the sum of a square number and a factorial in 3 ways. The next number with this property is 46249.

References

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 140

References

"Sloane's A028442 : Numbers n such that Mertens' function is zero". OEIS Foundation.
"Sloane's A000326 : Pentagonal numbers". OEIS Foundation.
"Sloane's A001844 : Centered square numbers". OEIS Foundation.
"Sloane's A014080 : Factorions". OEIS Foundation.
"A359013 - OEIS". OEIS Foundation.

Info: Wikipedia Source

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