A369626 a(n) is the number of permutations of [n] which avoid the patterns 1234, 1324, and 2413.

1, 1, 2, 6, 21, 75, 265, 925, 3201, 11017, 37793, 129393, 442497, 1512225, 5165953, 17643457, 60250113, 205729921, 702452225, 2398414593, 8188884993

Offset: 0

Author

Matt Slattery-Holmes, Feb 05 2024

Keywords

• nonn
• more

Examples

			All 6 of the permutations of length 3 avoid all patterns of length 4, so a(3)=6.
		

Crossrefs

Cf. A033321 (avoiding 1234, 1324, and 1342), A369431 (avoiding 1234, 1324, 1342, and 2413).

Extensions

a(11)-a(20) from Martin Ehrenstein, Feb 24 2024