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

0,3

Links

Table of n, a(n) for n=0..20.

Example

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).

Sequence in context: A116806 A116736 A116820 * A294815 A116751 A116823

Adjacent sequences: A369623 A369624 A369625 * A369627 A369628 A369629

Keyword

nonn,more

Author

Matt Slattery-Holmes, Feb 05 2024

Extensions

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

Status

approved