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A221720 as a simple table

na(n)
11
21
32
45
512
626
749
883
9129
10187
11257
12339
13433
14539
15657
16787
17929
181083
191249
201427
211617
221819
232033
242259
252497
262747
273009
283283
293569
303867
314177
324499
334833
345179
355537
365907
376289
386683
397089
407507
417937
428379
438833
449299
459777
4610267
4710769
4811283
4911809
5012347

[1,1,2,5,12,26,49,83,129,187,257,339,433,539,657,
 787,929,1083,1249,1427,1617,1819,2033,2259,2497,
 2747,3009,3283,3569,3867,4177,4499,4833,5179,5537,
 5907,6289,6683,7089,7507,7937,8379,8833,9299,9777,
 10267,10769,11283,11809,12347]