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A172520 as a triangular array

1
23
245
3467
25689
45781011
2579101213
468911121415
367101113141617
45910121315161819
2781012141517182021
679111314161719202223
2581112

A172520 as a square array

1223242434262
344555665775
56677879898
788991010101111
91010111112121312
11121213131414
131414151516
1516161717
17181819
192020
2122
23
1223242434262
344555665775
56677879898
788991010101111
91010111112121312
11121213131414
131414151516
1516161717
17181819
192020
2122
23