A275541 (n)! + (n + 1)!!/(n + 1) - 2

0, 0, 1, 6, 25, 126, 733, 5086, 40423, 363262, 3629743, 39920638, 479011993, 6227066878, 87178426333, 1307675013118, 20922791915023, 355687438417918, 6402373740187423, 121645100594626558, 2432902008831369073

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Crossrefs

Cf. A006882, A128882.

Sequence in context: A099359 A073967 A188207 * A082430 A136593 A012293

Adjacent sequences: A275538 A275539 A275540 * A275542 A275543 A275544

Keyword

nonn,easy

Author

Olivier Gérard, Aug 01 2016

Status

approved