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 A173850 Number of permutations of 1..n with no adjacent pair summing to n+10. 0
 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 32659200, 399168000, 4470681600, 64186214400, 855496857600, 14073067008000, 216999220838400, 4018570511155200, 70276861528473600, 1445722935681024000, 28251875803447296000, 638889942904012800000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS If a(n,k) is the number of permutations of 1..n with no adjacent pair summing to n+k, then a(n,k) = a(n,k+1) for n+k even. LINKS FORMULA k = 10; m = max(0, floor((n-k+1)/2)); a(n,k) = Sum_{j=0..m} (-2)^j * binomial(m,j)*(n-j)!. CROSSREFS Sequence in context: A276844 A273697 A177281 * A154658 A179369 A267390 Adjacent sequences:  A173847 A173848 A173849 * A173851 A173852 A173853 KEYWORD nonn AUTHOR R. H. Hardin, Feb 26 2010 EXTENSIONS Comment proved by William Keith, formula from Max Alekseyev, on the Sequence Fans Mailing List More terms from Alois P. Heinz, Jan 09 2017 STATUS approved

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Last modified December 8 04:31 EST 2019. Contains 329850 sequences. (Running on oeis4.)