login

A131520 as a simple table

na(n)
12
26
312
422
540
674
7140
8270
9528
101042
112068
124118
138216
1416410
1532796
1665566
17131104
18262178
19524324
201048614
212097192
224194346
238388652
2416777262
2533554480
2667108914
27134217780
28268435510
29536870968
301073741882
312147483708

[2,6,12,22,40,74,140,270,528,1042,2068,4118,8216,
 16410,32796,65566,131104,262178,524324,1048614,
 2097192,4194346,8388652,16777262,33554480,
 67108914,134217780,268435510,536870968,1073741882,
 2147483708]