Search a number
alternating n.  and  undulating n.

First numbers that belong to both sets:

101, 121, 141, 161, 181, 212, 232, 252, 272, 292, 303, 323, 343, 363, 383, 414, 434, 454, 474, 494, 505, 525, 545, 565, 585, 616, 636, 656, 676, 696, 707, 727, 747, 767, 787, 818, 838, 858, 878, 898, 909, 929, 949, 969, 989, 1010, 1212, 1414, 1616, 1818, 2121, 2323, 2525, 2727, 2929, 3030, 3232, 3434, 3636, 3838, 4141, 4343, 4545, 4747, 4949, 5050, 5252, 5454, 5656, 5858, 6161, 6363, 6565, 6767, 6969, 7070, 7272, 7474, 7676, 7878, 8181, 8383, 8585, 8787, 8989, 9090, 9292, 9494, 9696, 9898, 10101, 12121, 14141, 16161, 18181, 21212, 23232, 25252, 27272, 29292, 30303, 32323, 34343, 36363, 38383, 41414, 43434, 45454, 47474, 49494, 50505, 52525, 54545, 56565, 58585, 61616, 63636, 65656, 67676, 69696, 70707, 72727, 74747, 76767, 78787, 81818, 83838, 85858, 87878, 89898, 90909, 92929, 94949, 96969, 98989, 101010, 121212, 141414, 161616, 181818, 212121, 232323, 252525, 272727, 292929, 303030, 323232, 343434, 363636, 383838, 414141, 434343, 454545, 474747, 494949, 505050, 525252, 545454, 565656, 585858, 616161, 636363, 656565, 676767, 696969, 707070, 727272, 747474, 767676, 787878, 818181, 838383, 858585, 878787, 898989, 909090, 929292, 949494, 969696, 989898, 1010101, 1212121, 1414141, 1616161, 1818181, 2121212, 2323232, 2525252, 2727272, 2929292, 3030303, 3232323, 3434343, 3636363, 3838383, 4141414, 4343434, 4545454, 4747474, 4949494, 5050505, 5252525, 5454545, 5656565, 5858585, 6161616, 6363636, 6565656, 6767676, 6969696, 7070707, 7272727, 7474747, 7676767, 7878787, 8181818, 8383838, 8585858, 8787878, 8989898, 9090909, 9292929, 9494949, 9696969, 9898989, 10101010, 12121212, 14141414, 16161616, 18181818, 21212121, 23232323, 25252525, 27272727, 29292929, 30303030, 32323232, 34343434, 36363636, 38383838, 41414141, 43434343, 45454545, 47474747, 49494949, 50505050, 52525252, 54545454, 56565656, 58585858, 61616161, 63636363, 65656565, 67676767, 69696969, 70707070, 72727272, 74747474, 76767676, 78787878, 81818181, 83838383, 85858585, 87878787, 89898989, 90909090, 92929292, 94949494, 96969696, 98989898, 101010101, 121212121, 141414141, 161616161, 181818181, 212121212, 232323232, 252525252, 272727272, 292929292.

Some larger examples :