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序列有无穷多个项。事实上,对于任何大于0的整数,我们有(6*t^2)^3+(6*t^3-1)^3=(6*t^3+1)^3-2,因此pi((6*t^2)^3+(6*t^3-1)^3)=pi((6*t^3+1)^3),因为(6*t^3+1)^3和(6*t^3+1)^3-1都不是素数。
关于方程pi(x^3+y^3)=pi(z^3),其中0<x<=y<z,正好有70个解,其中z<=2700。它们是(x,y,z)=(5,6,7),(6,8,9),(7,10,11),(9,10,12),(15,33,34),(23,44,46),(24,47,49),(43,58,65),(41,86,89),(47,91,95),(64,94,103),(95,106,127),(71,138,144),(73,144,150),(54,161,163),(135,138,172),(128,188,206),(55,235,236),(135,235,249),(197,212,258),(159,256,275),(142,276,288),(146,288,300),(192,282,309),(161,297,312),(96,383,385),(252,345,385),(390,391,492),(334,438,495),(372,426,505),(426,486,577),(297,619,641),(353,650,683),(242,720,729),(244,729,738),(150,749,751),(602,659,796),(161,833,835),(470,825,873),(566,823,904),(668,876,990),(514,947,995),(744,852,1010),(791,812,1010),(509,1120,1154),(852,972,1154),(236,1207,1210),(216,1295,1297),(459,1293,1312),(915,1259,1403),(484,1440,1458),(488,1458,1476),(300,1498,1502),(368,1537,1544),(511,1609,1626),(420,1652,1661),(1278,1458,1731),(1132,1646,1808),(1033,1738,1852),(1241,1808,1985),(1010,1897,1988),(1582,1624,2020),(294,2057,2059),(237,2106,2107),(732,2187,2214),(575,2292,2304),(577,2304,2316),(1518,2141,2370),(1611,2189,2448),(432,2590,2594).
回想一下费马最后定理,它断言不定方程x^n+y^n=z^n的n>2和x,y,z>0没有解。1936年,K·马勒发现
(9*t^3+1)^3+(9*t ^4)^3-(9*t ^4+3*t)^3=1。
猜想:(i)对于{x,y}不等于{1,z}的任何整数n>3和x,y,z>0,我们有|x^n+y^n-z^n|>=2^n-2,除非n=5,{x,y}={13,16}和z=17。
(ii)对于任何整数n>3和x,y,z>0,其中{x,y}不包含z,则存在一个素数p,其中x^n+y^n<p<z^n或z^n<p<x^n+y^n,除非n=5,{x,y}={13,16}和z=17。
(iii)对于x不等于z的任何整数n>3、x>y>=0和z>0,总是存在一个素数p与x^n-y^n<p<z^n或z^n<p<x^n-y ^n。
我们已经验证了n=4..10和0<x,y,z<=1700的猜想的部分(i)。
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