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A226305 as a simple table

na(n)
11
21
33
43
515
61
763
85
921
101
111023
125
134095
141
1517
1617
1765535
181
19262143
2017
2165
221
234194303
2417
2569905
261
274161
2865
29268435455
301
311073741823
32257
331025
341
3553261
3613
3768719476735
381
394097
40257
411099511627775
421
434398046511103
441025
453133
461
4770368744177663
48257
4969810262081
501
5165537
524097

[1,1,3,3,15,1,63,5,21,1,1023,5,4095,1,17,17,65535,
 1,262143,17,65,1,4194303,17,69905,1,4161,65,
 268435455,1,1073741823,257,1025,1,53261,13,
 68719476735,1,4097,257,1099511627775,1,
 4398046511103,1025,3133,1,70368744177663,257,
 69810262081,1,65537,4097]