Number of permutations of [n] with exactly two (possibly overlapping) occurrences of some of the consecutive patterns 123, 1432, 2431, 3421.
A228422
Number of permutations of [n] with exactly two (possibly overlapping) occurrences of some of the consecutive patterns 123, 1432, 2431, 3421.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =14a(6) =164a(7) =1589a(8) =15034a(9) =139465a(10) =1334945a(11) =13108425a(12) =134906641a(13) =1443572465a(14) =16238742806a(15) =190546010823
External references
- oeis: A228422