A308434 n! + n!!.

2, 2, 4, 9, 32, 135, 768, 5145, 40704, 363825, 3632640, 39927195, 479047680, 6227155935, 87178936320, 1307676395025, 20922800209920, 355687462555425, 6402373891522560, 121645101063561075, 2432902011892531200, 51090942185458750575, 1124000727859357286400

Offset

0,1

Links

Table of n, a(n) for n=0..22.

Example

5! = 120 and 5!! = 15, so a(5) = 135.

Mathematica

Table[n!+n!!, {n, 0, 30}]

Crossrefs

A000142(n)+A006882(n).

Sequence in context: A052925 A006182 A267339 * A121623 A267347 A296386

Adjacent sequences: A308431 A308432 A308433 * A308435 A308436 A308437

Keyword

nonn,easy

Author

Harvey P. Dale, May 26 2019

Status

approved