A378297 - cp's OEIS frontend

A378297 Squarefree semiprimes k that remain squarefree semiprimes for exactly two iterations of the map k -> 2*k+1.

n	a(n)
1	38
2	46
3	106
4	129
5	133
6	201
7	235
8	334
9	335
10	381
11	417
12	458
13	489
14	538
15	579
16	583
17	597
18	623
19	626
20	685
21	689
22	694
23	767
24	781
25	898
26	921
27	1073
28	1082
29	1099
30	1214
31	1226
32	1227
33	1234
34	1285
35	1299
36	1315
37	1385
38	1486
39	1514
40	1517
41	1546
42	1603
43	1631
44	1646
45	1799
46	1817
47	1819
48	1841

[38, 46, 106, 129, 133, 201, 235, 334, 335, 381, 417, 458, 489, 538, 579, 583, 597, 623, 626, 685, 689, 694, 767, 781, 898, 921, 1073, 1082, 1099, 1214, 1226, 1227, 1234, 1285, 1299, 1315, 1385, 1486, 1514, 1517, 1546, 1603, 1631, 1646, 1799, 1817, 1819, 1841]

cp's OEIS Frontend

A378297 Squarefree semiprimes k that remain squarefree semiprimes for exactly two iterations of the map k -> 2*k+1.

Table of values

List of values