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palindromic n.  and  undulating n.

First numbers that belong to both sets:

101, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 454, 464, 474, 484, 494, 505, 515, 525, 535, 545, 565, 575, 585, 595, 606, 616, 626, 636, 646, 656, 676, 686, 696, 707, 717, 727, 737, 747, 757, 767, 787, 797, 808, 818, 828, 838, 848, 858, 868, 878, 898, 909, 919, 929, 939, 949, 959, 969, 979, 989, 10101, 12121, 13131, 14141, 15151, 16161, 17171, 18181, 19191, 20202, 21212, 23232, 24242, 25252, 26262, 27272, 28282, 29292, 30303, 31313, 32323, 34343, 35353, 36363, 37373, 38383, 39393, 40404, 41414, 42424, 43434, 45454, 46464, 47474, 48484, 49494, 50505, 51515, 52525, 53535, 54545, 56565, 57575, 58585, 59595, 60606, 61616, 62626, 63636, 64646, 65656, 67676, 68686, 69696, 70707, 71717, 72727, 73737, 74747, 75757, 76767, 78787, 79797, 80808, 81818, 82828, 83838, 84848, 85858, 86868, 87878, 89898, 90909, 91919, 92929, 93939, 94949, 95959, 96969, 97979, 98989, 1010101, 1212121, 1313131, 1414141, 1515151, 1616161, 1717171, 1818181, 1919191, 2020202, 2121212, 2323232, 2424242, 2525252, 2626262, 2727272, 2828282, 2929292, 3030303, 3131313, 3232323, 3434343, 3535353, 3636363, 3737373, 3838383, 3939393, 4040404, 4141414, 4242424, 4343434, 4545454, 4646464, 4747474, 4848484, 4949494, 5050505, 5151515, 5252525, 5353535, 5454545, 5656565, 5757575, 5858585, 5959595, 6060606, 6161616, 6262626, 6363636, 6464646, 6565656, 6767676, 6868686, 6969696, 7070707, 7171717, 7272727, 7373737, 7474747, 7575757, 7676767, 7878787, 7979797, 8080808, 8181818, 8282828, 8383838, 8484848, 8585858, 8686868, 8787878, 8989898, 9090909, 9191919, 9292929, 9393939, 9494949, 9595959, 9696969, 9797979, 9898989, 101010101, 121212121, 131313131, 141414141, 151515151, 161616161, 171717171, 181818181, 191919191, 202020202, 212121212, 232323232, 242424242, 252525252, 262626262, 272727272, 282828282, 292929292, 303030303, 313131313, 323232323, 343434343, 353535353, 363636363, 373737373, 383838383, 393939393, 404040404, 414141414, 424242424, 434343434, 454545454, 464646464, 474747474, 484848484, 494949494, 505050505.

Some larger examples :