A346719 a(n) is the number of positive Euler permutations of order 2*n. Bisection (even indices) of A347601.

1, 0, 7, 102, 8109, 642220, 89458803, 15935870034, 3858227881945, 1176448390679256, 447692501190569823, 206713705368363820990, 114132862919751113790597, 74179275137980421348697732, 56081703047542413155379531979, 48790316146471264354636437276330, 48400301382766335524903922737193393

Offset

0,3

Comments

For definitions and comments see A347601.

Links

Table of n, a(n) for n=0..16.

Formula

a(n) + A346720(n) = A000166(2n) (rencontres numbers).

a(n) - A346720(n) = A000364(n) (Euler secant numbers).

a(n) = subfactorial(2*n) / 2 + Im(PolyLog(-2*n, i)).

Maple

A346719 := n -> (A000166(2*n) + euler(2*n)) / 2:
seq(A346719(n), n = 0..16);

Mathematica

A346719[n_] := Subfactorial[2 n]/2 + Im[PolyLog[-2 n, I]];
Table[A346719[n], {n, 0, 16}]

Crossrefs

Cf. A347601, A346720, A000166, A000364, A347602.

Sequence in context: A348887 A358159 A203356 * A223239 A140633 A142400

Adjacent sequences: A346716 A346717 A346718 * A346720 A346721 A346722

Keyword

nonn

Author

Peter Luschny, Sep 09 2021

Status

approved