145 (number)

145 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 < 145. In four of those bases, it is a strong pseudoprime: 1, 12, 17, and 144. The Mertens function returns 0.https://oeis.org/A028442 Sloane's A028442 : Numbers n such that Mertens' function is zero The On-Line Encyclopedia of Integer Sequences OEIS Foundation 2016-05-28 145 is a pentagonal numberhttps://oeis.org/A000326 Sloane's A000326 : Pentagonal numbers The On-Line Encyclopedia of Integer Sequences OEIS Foundation 2016-05-28 and a centered square number.https://oeis.org/A001844 Sloane's A001844 : Centered square numbers The On-Line Encyclopedia of Integer Sequences OEIS Foundation 2016-05-28 . 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. , making it a factorion.https://oeis.org/A014080 Sloane's A014080 : Factorions The On-Line Encyclopedia of Integer Sequences OEIS Foundation 2016-05-28 The only other numbers that have this property are 1, 2 and 40585. , 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.A359013 - OEIS https://oeis.org/A359013 2022-12-11 The On-Line Encyclopedia of Integer Sequences OEIS Foundation References Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 140 External links The Natural Number 145 Parker Matt 145 and the Melancoil http://www.numberphile.com/videos/melancoil.html Numberphile Brady Haran 2013-04-06 https://web.archive.org/web/20130514215714/http://www.numberphile.com/videos/melancoil.html 2013-05-14 dead 1 Category:Integers