A375022 Number of permutations of n (distinct) elements from [2n] without consecutive adjacent values.

1, 2, 6, 48, 650, 11604, 253890, 6572176, 196467642, 6660672060, 252504829346, 10584157180920, 486052773276954, 24267623565599428, 1308816525199710210, 75828568345500497184, 4696852810090223180090, 309727816544792336406156, 21664419864179709448539042

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..366

Formula

a(n) = A338526(2n,n).

Example

a(0) = 1: the empty permutation.
a(1) = 2: 1, 2.
a(2) = 6: 13, 14, 24, 31, 41, 42.
a(3) = 48: 135, 136, 142, 146, 152, 153, 162, 163, 164, 241, 246, 251, 253, 261, 263, 264, 314, 315, 316, 351, 352, 361, 362, 364, 413, 415, 416, 425, 426, 461, 462, 463, 513, 514, 516, 524, 526, 531, 536, 613, 614, 615, 624, 625, 631, 635, 641, 642.

Crossrefs

Cf. A338526.

Sequence in context: A052735 A365286 A052717 * A365287 A129464 A175430

Adjacent sequences: A375019 A375020 A375021 * A375023 A375024 A375025

Keyword

nonn

Author

Alois P. Heinz, Aug 04 2024

Status

approved