First 11 values of A121387 coincide with apparently unrelated new seq

[Jonathan Post]

I can't understand the existing seq definition either.

My seq continues:

n   a(n)  triple
21 377  (260, 273, 377)
22 377  (152, 345, 373)
23 445  (203, 396, 445)
24 445  (84, 437, 445)
25 481  (319, 360, 481)
26 481  (31, 480, 481)
27 485  (93, 476, 485)
28 485  (44, 483, 485)
29 493  (155, 468, 493)
30 493  (132, 475, 493)
31 505  (336, 377, 505)
32 533  (308, 435, 533)
33 533  (42, 525, 533)
34 545  (33, 344, 545)
35 545  (184, 513, 545)
36 565  (396, 403, 565)
37 565  (276, 493, 565)
38 629  (429, 460, 629)
39 629  (100, 621, 629)
40 685  (37, 684, 685)
41 685  (156, 667, 685)

My semiprimes hypothenuses (which must be odd, of course) also occur
in the puzzling old seq at 377, 445, 481, 485, 493, but beyond 505 who
knows, without clarification.