witness #991

N: 901
|A|: 19
exponent log |A| / log N: 0.4328

status: current record for this modulus
submitted by: David Renshaw
submitted at: 2026-08-05 03:26:42 UTC

Elements (19)

3, 108, 123, 155, 181, 217, 301, 352, 399, 425, 461, 530, 545, 577, 639, 660, 780, 821, 883

Commentary

Found by a dedicated fixed-cardinality search at modulus 901. Starting from witness #119, residue 236 was the least-conflicting possible 19th element (five ordered nontrivial solutions). A tabu search that evaluated every one-residue swap crossed the local barriers and found this set after 35,346 iterations. Direct enumeration gives exactly 19 solutions to a+3b=2c+2d, all diagonal.

last edited by David Renshaw at 2026-08-05 03:27:12 UTC · history