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A082426
a(n) = floor(n*n!/2 + 1).
0
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]
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
KEYWORD
nonn,easy
AUTHOR
Benoit Cloitre, Apr 24 2003
EXTENSIONS
Definition corrected by Georg Fischer, May 15 2024
STATUS
approved