Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,7} for all i=1,...,n.
A387021
Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,7} for all i=1,...,n.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =2a(10) =3a(11) =5a(12) =7a(13) =10a(14) =13a(15) =17a(16) =21a(17) =25a(18) =30a(19) =36a(20) =46a(21) =59a(22) =81a(23) =109a(24) =153a(25) =207a(26) =277a(27) =361a(28) =463a(29) =589
External references
- oeis: A387021