A281913 - cp's OEIS frontend

A281913 Number of ordered integer pairs (b,c), with -n<=b<=n, -n<=c<=n, such that both roots of 2x^2+bx+c=0 are rational and b and c are not both even.

n	a(n)
1	4
2	4
3	12
4	12
5	22
6	24
7	36
8	36
9	50
10	54
11	64
12	68
13	78
14	82
15	100
16	100
17	110
18	118
19	128
20	132
21	150
22	154
23	164
24	168
25	182
26	186
27	204
28	208
29	218
30	230
31	240
32	240
33	258
34	262
35	280
36	288
37	298
38	302
39	320
40	324
41	334
42	346
43	356
44	360
45	386
46	390
47	400
48	404
49	418
50	426

[4, 4, 12, 12, 22, 24, 36, 36, 50, 54, 64, 68, 78, 82, 100, 100, 110, 118, 128, 132, 150, 154, 164, 168, 182, 186, 204, 208, 218, 230, 240, 240, 258, 262, 280, 288, 298, 302, 320, 324, 334, 346, 356, 360, 386, 390, 400, 404, 418, 426]

cp's OEIS Frontend

A281913 Number of ordered integer pairs (b,c), with -n<=b<=n, -n<=c<=n, such that both roots of 2x^2+bx+c=0 are rational and b and c are not both even.

Table of values

List of values

n	a(n)
1	4
2	4
3	12
4	12
5	22
6	24
7	36
8	36
9	50
10	54
11	64
12	68
13	78
14	82
15	100
16	100
17	110
18	118
19	128
20	132
21	150
22	154
23	164
24	168
25	182
26	186
27	204
28	208
29	218
30	230
31	240
32	240
33	258
34	262
35	280
36	288
37	298
38	302
39	320
40	324
41	334
42	346
43	356
44	360
45	386
46	390
47	400
48	404
49	418
50	426

n	a(n)
1	4
2	4
3	12
4	12
5	22
6	24
7	36
8	36
9	50
10	54
11	64
12	68
13	78
14	82
15	100
16	100
17	110
18	118
19	128
20	132
21	150
22	154
23	164
24	168
25	182
26	186
27	204
28	208
29	218
30	230
31	240
32	240
33	258
34	262
35	280
36	288
37	298
38	302
39	320
40	324
41	334
42	346
43	356
44	360
45	386
46	390
47	400
48	404
49	418
50	426

n	a(n)
1	4
2	4
3	12
4	12
5	22
6	24
7	36
8	36
9	50
10	54
11	64
12	68
13	78
14	82
15	100
16	100
17	110
18	118
19	128
20	132
21	150
22	154
23	164
24	168
25	182
26	186
27	204
28	208
29	218
30	230
31	240
32	240
33	258
34	262
35	280
36	288
37	298
38	302
39	320
40	324
41	334
42	346
43	356
44	360
45	386
46	390
47	400
48	404
49	418
50	426