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 A230348 Number of permutations of [2n+8] in which the longest increasing run has length n+8. 3
 1, 18, 349, 7672, 192240, 5454144, 173606040, 6143195520, 239656253760, 10231052832000, 474832908950400, 23819880180096000, 1284985968634368000, 74207855717259264000, 4569213387521502720000, 298885288012537901875200, 20702796608070625112064000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also the number of ascending runs of length n+8 in the permutations of [2n+8]. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..300 FORMULA a(n) = (n^3+18*n^2+90*n+89)*(2*n+8)!/(n+10)! for n>0, a(0) = 1. a(n) = A008304(2*n+8,n+8) = A122843(2*n+8,n+8). MAPLE a:= proc(n) option remember; `if`(n<2, 1+17*n, 2*(n+4)*(2*n+7)*       (n^3+18*n^2+90*n+89)*a(n-1)/((n+10)*(n^3+15*n^2+57*n+16)))     end: seq(a(n), n=0..25); CROSSREFS A diagonal of A008304, A122843. Sequence in context: A158590 A143168 A127585 * A182609 A320764 A086502 Adjacent sequences:  A230345 A230346 A230347 * A230349 A230350 A230351 KEYWORD nonn AUTHOR Alois P. Heinz, Oct 16 2013 STATUS approved

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Last modified March 31 19:16 EDT 2020. Contains 333151 sequences. (Running on oeis4.)