- n=300-500k, 57k left (58, 386, 464, 494, 688, 844, 928, 982, 1102, 1274, 1318, 1514, 1582, 1642, 1646, 1796, 1948, 1996, 2008, 2218, 2294, 2326, 2336, 2368, 2452, 2474, 2568, 2722, 2776, 2804, 2932, 2984, 3112, 3208, 3228, 3326, 3364, 3418, 3464, 3502, 3772, 3776, 4064, 4274, 4334, 4376, 4378, 4514, 4586, 4684, 4844, 4918, 4946, 4978, 5036, 5294, 5366)
- runtime 26min-1h21min (AVX@3.8Ghz)

576*53^113129-1 found by NudgeyNMR
2046*53^113414-1 found by walli
610*53^125737-1 found by mmonnin
2338*53^128165-1 found by Doug
4882*53^128251-1 found by kraDen
1628*53^138940-1 found by Tim B
3958*53^140565-1 found by Tim B
5140*53^145173-1 found by Tim B
208*53^158365-1 found by Dingo
3802*53^179867-1 found by mmonnin
3958*53^184817-1 found by Doug
5174*53^199016-1 found by Dark Angel
478*53^220497-1 found by IDEA
4404*53^235589-1 found by DougB
4404*53^240521-1 found by DougB
1762*53^250071-1 found by grcpool.5
3262*53^257191-1 found by grcpool.com-3
130*53^289743-1 found by Shaman
3596*53^352762-1 found by 2yHHCbDTnTh8r7Qa8AMYns29cz36
4708*53^404689-1 found by entity (TOP5000)
5096*53^417366-1 found by entity (TOP5000)
5252*53^459192-1 found by vaughan (TOP5000)