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41 (forty-one) is the natural number following 40 and preceding 42. ==In mathematics== Forty-one is the 13th smallest prime number. The next is forty-three, with which it comprises a twin prime. It is also the sum of the first six prime numbers (2 + 3 + 5 + 7 + 11 + 13), and the sum of three primes (11 + 13 + 17). Forty-one is also the 12th supersingular prime, a Sophie Germain prime and a Newman–Shanks–Williams prime. 41 is the smallest Sophie Germain prime to start a Cunningham chain of the first kind of three terms, . It is an Eisenstein prime, with no imaginary part and real part of the form 3''n'' − 1. 41 is a Proth prime as it is 5 × 23 + 1. 41 is the largest lucky number of Euler; it figures in the polynomial , which yields primes for . 41 is the sum of two squares, 42 + 52. Adding up the sums of divisors for 1 through 7 yields 41. 41 is the smallest integer whose reciprocal has a 5-digit repetend. That is a consequence of the fact that 41 is a factor of 99999. It is a centered square number. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「41 (number)」の詳細全文を読む スポンサード リンク
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