A332955 a(0) = 1 and a(n) = A309807(n) - A309807(n-1) for n > 0.

1, 0, 0, 1, 1, 3, 3, 10, 11, 30, 48, 114, 166, 486, 727, 1643, 3193, 7619, 12489, 30781, 52007, 123418, 248386, 520902, 909701, 2349536, 4417148, 9055904, 18451951, 41215779, 77052793, 186393151, 350380117, 769533521

Offset

0,6

Comments

See A309807.

Links

Table of n, a(n) for n=0..33.

Prog

(Ruby)
def A(n)
  (1..n).to_a.permutation.select{|i| (1..n - 1).all?{|j| i[j - 1] * (j + 1) > i[j] * j}}.size
end
def A332955(n)
  a = (0..n).map{|i| A(i)}
  [1] + (1..n).map{|i| a[i] - a[i - 1]}
end
p A332955(10)

Crossrefs

Cf. A309807.

Sequence in context: A321397 A128015 A233256 * A355089 A218953 A081809

Adjacent sequences: A332952 A332953 A332954 * A332956 A332957 A332958

Keyword

nonn

Author

Seiichi Manyama, Mar 04 2020

Extensions

a(23)-a(25) from Giovanni Resta, Mar 04 2020

a(26)-a(33) from Bert Dobbelaere, Mar 15 2020

Status

approved