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A174969 as a simple table

na(n)
121
257
391
4111
5133
6183
7273
8343
9381
10507
11553
12651
13703
14813
15871
16931
17993
181057
191191
201261
211333
221407
231561
241641
251807
261893
271981
282071
292163
302257
312353
322451
332653
342757
352863
363081
373193
383423
393661
403783
414033
424161
434291
444557
454693
464971

[21,57,91,111,133,183,273,343,381,507,553,651,703,
 813,871,931,993,1057,1191,1261,1333,1407,1561,
 1641,1807,1893,1981,2071,2163,2257,2353,2451,2653,
 2757,2863,3081,3193,3423,3661,3783,4033,4161,4291,
 4557,4693,4971]