Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,-1,3} for all i=1,...,n.
A079999
Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,-1,3} for all i=1,...,n.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =4a(10) =4a(11) =5a(12) =7a(13) =10a(14) =16a(15) =22a(16) =29a(17) =40a(18) =60a(19) =84a(20) =118a(21) =165a(22) =230a(23) =330a(24) =466a(25) =653a(26) =919a(27) =1297a(28) =1831a(29) =2585
External references
- oeis: A079999