Number of permutations of length n with exactly 2 occurrences of the pattern 2-13.
A094218
Number of permutations of length n with exactly 2 occurrences of the pattern 2-13.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =2a(4) =25a(5) =198a(6) =1274a(7) =7280a(8) =38556a(9) =193800a(10) =937992a(11) =4412826a(12) =20309575a(13) =91861770a(14) =409704750a(15) =1806342720a(16) =7887861960a(17) =34166674800a(18) =146977222320a(19) =628521016500
External references
- oeis: A094218