A260550 - cp's OEIS frontend

A260550 a(n) is the number of 2 X 2 matrices with entries in {1, ..., n} that are not the product of two 2 X 2 positive integer matrices.

n	a(n)
1	1
2	15
3	75
4	237
5	559
6	1157
7	2055
8	3471
9	5449
10	8131
11	11633
12	16361
13	22041
14	29349
15	38329
16	48839
17	61325
18	76479
19	93957
20	114717
21	138041
22	164153
23	194505
24	229625
25	268259
26	311031
27	359719
28	413245
29	472145
30	537835
31	608837
32	688121
33	774877
34	867549
35	971403
36	1080637
37	1198233
38	1326059
39	1467029
40	1617451
41	1777881
42	1948219
43	2132381
44	2329081
45	2539351

[1, 15, 75, 237, 559, 1157, 2055, 3471, 5449, 8131, 11633, 16361, 22041, 29349, 38329, 48839, 61325, 76479, 93957, 114717, 138041, 164153, 194505, 229625, 268259, 311031, 359719, 413245, 472145, 537835, 608837, 688121, 774877, 867549, 971403, 1080637, 1198233, 1326059, 1467029, 1617451, 1777881, 1948219, 2132381, 2329081, 2539351]

cp's OEIS Frontend

A260550 a(n) is the number of 2 X 2 matrices with entries in {1, ..., n} that are not the product of two 2 X 2 positive integer matrices.

Table of values

List of values