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 A230344 Number of permutations of [2n+4] in which the longest increasing run has length n+4. 3
 1, 10, 137, 2360, 49236, 1209936, 34288800, 1102187520, 39656131200, 1579837754880, 69064610186880, 3288126441600000, 169388400557376000, 9389435419203840000, 557323393281887232000, 35272416767753797632000, 2371290445442664345600000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also the number of ascending runs of length n+4 in the permutations of [2n+4]. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..300 FORMULA a(n) = (n^3+10*n^2+30*n+29)*(2*n+4)!/(n+6)! for n>0, a(0) = 1. a(n) = A008304(2*n+4,n+4) = A122843(2*n+4,n+4). MAPLE a:= proc(n) option remember; `if`(n<2, 1+9*n, 2*(2*n+3)*(n+2)*       (n^3+10*n^2+30*n+29)*a(n-1)/((n+6)*(n^3+7*n^2+13*n+8)))     end: seq(a(n), n=0..25); CROSSREFS A diagonal of A008304, A122843. Sequence in context: A096619 A276131 A003377 * A318594 A065593 A089834 Adjacent sequences:  A230341 A230342 A230343 * A230345 A230346 A230347 KEYWORD nonn AUTHOR Alois P. Heinz, Oct 16 2013 STATUS approved

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)