The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {2,3,4} for all i from 1 to n-1.
A174704
The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {2,3,4} for all i from 1 to n-1.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =0a(4) =2a(5) =14a(6) =60a(7) =152a(8) =256a(9) =464a(10) =1124a(11) =3114a(12) =8324a(13) =20166a(14) =44958a(15) =97666a(16) =217792a(17) =501356a(18) =1163776a(19) =2668126a(20) =6006712a(21) =13363390a(22) =29660118a(23) =66006498a(24) =147147006a(25) =327471130a(26) =725850010a(27) =1602363242a(28) =3527859498a(29) =7756716420
External references
- oeis: A174704