A338121 - cp's OEIS frontend

A338121 Positive integers not congruent to 0 mod 6 which cannot be written as x^2 + y^2 + z^2 + w^2 with x + y = 4^k for some positive integer k, where x, y, z, w are nonnegative integers.

n	a(n)
1	1
2	2
3	3
4	4
5	5
6	7
7	31
8	43
9	67
10	79
11	85
12	87
13	103
14	115
15	475
16	643
17	1015
18	1399
19	1495
20	1723
21	1819
22	1939
23	1987

[1, 2, 3, 4, 5, 7, 31, 43, 67, 79, 85, 87, 103, 115, 475, 643, 1015, 1399, 1495, 1723, 1819, 1939, 1987]