Search a number
alternating n.  and  interprime n.

First numbers that belong to both sets:

4, 6, 9, 12, 18, 21, 30, 34, 45, 50, 56, 69, 72, 76, 81, 105, 129, 165, 236, 254, 270, 274, 309, 363, 381, 414, 432, 436, 501, 610, 618, 636, 650, 656, 696, 705, 723, 741, 747, 765, 810, 816, 834, 858, 870, 909, 969, 987, 1016, 1032, 1036, 1050, 1056, 1078, 1092, 1230, 1234, 1254, 1278, 1290, 1294, 1416, 1436, 1452, 1456, 1476, 1496, 1616, 1632, 1698, 1854, 1872, 1878, 2105, 2121, 2303, 2349, 2541, 2585, 2703, 2709, 2745, 2783, 2985, 3030, 3252, 3258, 3410, 3610, 3634, 3672, 3694, 3812, 3852, 3858, 3870, 3898, 4105, 4189, 4521, 4587, 4785, 4925, 4947, 5010, 5016, 5218, 5232, 5276, 5410, 5418, 5434, 5474, 5478, 5492, 5652, 5658, 5676, 5810, 5850, 5854, 5874, 6107, 6147, 6185, 6525, 6549, 6749, 6903, 6909, 6969, 6987, 7016, 7050, 7074, 7212, 7216, 7250, 7290, 7414, 7454, 7458, 7494, 7614, 7630, 7870, 7878, 7892, 8169, 8185, 8323, 8341, 8507, 8541, 8589, 8703, 8725, 8781, 8985, 9012, 9054, 9416, 9432, 9438, 9450, 9470, 9476, 9494, 9616, 9630, 9678, 9814, 9836, 9854, 9858, 9894, 10101, 10107, 10161, 10187, 10363, 10507, 10521, 10545, 10563, 10785, 10923, 10965, 10983, 12345, 12385, 12507, 12561, 12741, 12903, 12909, 12921, 12947, 12963, 12981, 14125, 14187, 14325, 14727, 14763, 14769, 14781, 14943, 14949, 14963, 16107, 16185, 16701, 16761, 16929, 18129, 18309, 18321, 18347, 18369, 18547, 18585, 18707, 18725, 18765, 18905, 21012, 21018, 21078, 21216, 21258, 21298, 21450, 21474, 21492, 21496, 21612, 21632, 21678, 21692, 21810, 21830, 21876, 23014, 23034, 23058, 23076, 23218, 23274, 23292, 23616, 23670, 23674, 23816, 23832, 23876, 23890, 23896, 25032, 25092, 25250, 25410, 25450, 25470, 25636, 25650, 25670, 25676, 25698, 25810, 25830, 25858, 25870, 25896, 27014, 27070, 27256, 27274, 27418, 27434.

Some larger examples :