A025520 Least k>1 such that reverse of first n terms of A022303 repeats beginning at k-th term.

3, 2, 10, 15, 14, 13, 38, 146, 145, 144, 143, 142, 222, 221, 220, 219, 218, 217, 216, 215, 214, 374, 373, 372, 574, 573, 572, 571, 570, 569, 568, 567, 566, 565, 564, 563, 562, 561, 560, 7694, 7693, 7692, 7691, 7690, 7689, 7688, 7687, 7686, 7685, 7684, 7683, 7682