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 A342237 Table read by upward antidiagonals: T(n,k) is the number of strings of length k over an n-letter alphabet that begin with a palindrome of two or more letters; n, k >= 1. 2
 0, 0, 1, 0, 2, 1, 0, 3, 6, 1, 0, 4, 15, 14, 1, 0, 5, 28, 51, 30, 1, 0, 6, 45, 124, 165, 62, 1, 0, 7, 66, 245, 532, 507, 126, 1, 0, 8, 91, 426, 1305, 2164, 1551, 254, 1, 0, 9, 120, 679, 2706, 6605, 8788, 4683, 510, 1, 0, 10, 153, 1016, 5005, 16386, 33405, 35284, 14127, 1022, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS Peter Kagey, Antidiagonals n = 1..100, flattened FORMULA T(n,1)    = 0. T(n,2k)   = n*T(n,2k-1) + n^k - T(n,k). T(n,2k+1) = n*T(n,2k) + n^(k+1) - T(n,k+1). EXAMPLE Table begins: n\k | 1  2   3    4      5       6        7         8 ----+------------------------------------------------   1 | 0  1   1    1      1       1        1         1   2 | 0  2   6   14     30      62      126       254   3 | 0  3  15   51    165     507     1551      4683   4 | 0  4  28  124    532    2164     8788     35284   5 | 0  5  45  245   1305    6605    33405    167405   6 | 0  6  66  426   2706   16386    99186    595986   7 | 0  7  91  679   5005   35287   248731   1742839   8 | 0  8 120 1016   8520   68552   551496   4415048 CROSSREFS Rows: A000918 (n=2), A248122 (n=3), A249629 (n=4), A249638 (n=5), A249639 (n=6), A249640 (n=7), A249641 (n=8), A249642 (n=9), A249643 (n=10). Columns: A000384 (k=3), A007588 (k=4). Sequence in context: A035543 A350548 A105546 * A339030 A059297 A267222 Adjacent sequences:  A342234 A342235 A342236 * A342238 A342239 A342240 KEYWORD nonn,tabl AUTHOR Peter Kagey, Mar 06 2021 STATUS approved

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Last modified May 20 10:33 EDT 2022. Contains 353871 sequences. (Running on oeis4.)