A043003 n-th base 4 palindrome that starts with 1.

1, 5, 17, 21, 25, 29, 65, 85, 105, 125, 257, 273, 289, 305, 325, 341, 357, 373, 393, 409, 425, 441, 461, 477, 493, 509, 1025, 1105, 1185, 1265, 1285, 1365, 1445, 1525, 1545, 1625, 1705, 1785, 1805, 1885, 1965, 2045, 4097, 4161