Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=2, r=3, I={2}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =11a(5) =26a(6) =56a(7) =127a(8) =288a(9) =660a(10) =1500a(11) =3401a(12) =7729a(13) =17565a(14) =39930a(15) =90735a(16) =206176a(17) =468536a(18) =1064750a(19) =2419661a(20) =5498621a(21) =12495505a(22) =28395889a(23) =64529315a(24) =146642077a(25) =333242093a(26) =757288191a(27) =1720927502a(28) =3910785158a(29) =8887207808