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A261781 as a triangular array

1
01
023
041613
086613275
0162489241232541
032892554613064130604683
06431363072011403219502015592847293
012810888162396893490232796031162202075948545835

A261781 as a square array

100000000
1248163264128
31666248892313610888
13132924554630720162396
75123213064114032893490
541130601950202327960
46831559283116220
472932075948
545835
100000000
1248163264128
31666248892313610888
13132924554630720162396
75123213064114032893490
541130601950202327960
46831559283116220
472932075948
545835