第二问.可能OEIS没有收录
平方数的时候,解是$[a,b,y]=[\frac{t (2 U-t^2)}{U^2-t^2 U+1},\frac{t (U^2-1)}{U^2-t^2 U+1},t^2]$
非平方数的话,10000以内,下面这些数都可以,但不知道是什么规律
- 10,20,34,52,65,73,74,130,148,160,164,202,226,241,244,265,281,290,340,394,416,436,450,452,505,514,569,577,580,586,601,641,650,720,724,745,801,802,820,848,865,884,898,916,929,970,976,1044,1060,1073,1098,1105,1152,1154,1226,1252,1280,1305,1321,1345,1348,1354,1360,1396,1460,1546,1570,1585,1602,1604,1609,1620,1665,1684,1696,1721,1777,1780,1801,1802,1856,1865,1873,1924,2009,2020,2036,2041,2050,2080,2089,2164,2176,2180,2250,2305,2306,2314,2340,2404,2425,2448,2452,2473,2529,2545,2594,2626,2644,2720,2740,2785,2801,2848,2880,2890,2900,2929,2977,3044,3089,3121,3145,3152,3177,3202,3298,3305,3321,3361,3385,3466,3529,3530,3604,3636,3649,3673,3700,3744,3748,3769,3796,3825,3856,3865,3874,3881,3889,3970,3985,4034,4036,4052,4129,4176,4196,4234,4273,4304,4321,4384,4385,4420,4426,4441,4546,4561,4610,4705,4777,4801,4804,4810,4852,4880,4948,4969,5002,5044,5105,5140,5186,5200,5204,5209,5281,5364,5386,5410,5440,5473,5545,5584,5602,5620,5636,5641,5652,5706,5716,5760,5785,5825,5834,5905,5924,6052,6100,6145,6148,6154,6176,6201,6273,6274,6304,6352,6370,6401,6500,6505,6516,6544,6577,6626,6649,6660,6673,6689,6705,6730,6761,6841,6948,6961,6964,7060,7081,7114,7120,7121,7129,7156,7177,7202,7209,7234,7300,7380,7444,7456,7465,7489,7540,7561,7585,7650,7652,7690,7696,7760,7769,7780,7825,7840,7940,7969,7985,8066,8080,8116,8145,8161,8185,8194,8224,8226,8273,8320,8336,8345,8352,8425,8452,8521,8548,8665,8674,8676,8689,8705,8714,8770,8820,8865,8884,8948,8980,9001,9034,9040,9090,9124,9169,9225,9250,9281,9316,9346,9524,9529,9556,9610,9745,9760,9769,9802,9841,9866,9929
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