A082426 a(n) = floor(n*n!/2 + 1).

1, 3, 10, 49, 301, 2161, 17641, 161281, 1632961, 18144001, 219542401, 2874009601, 40475635201, 610248038401, 9807557760001, 167382319104001, 3023343138816001, 57621363351552001, 1155628453883904001, 24329020081766400001

Offset

1,2

Comments

Concatenate all the permutations of 1..n in lexicographical order. a(n) is the number of ascending runs. [David Scambler, May 26 2011]

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = A074143(n) + 1 for n >= 2. - Georg Fischer, May 15 2024

Maple

seq(floor(n*n!/2 + 1), n=1..20);

Crossrefs

Cf. A074143.

Sequence in context: A193281 A367754 A143921 * A359459 A054381 A102088

Adjacent sequences: A082423 A082424 A082425 * A082427 A082428 A082429

Keyword

nonn,easy

Author

Benoit Cloitre, Apr 24 2003

Extensions

Definition corrected by Georg Fischer, May 15 2024

Status

approved