A298881 a(0) = 0; for n>0, a(n) = 6*n!.

0, 6, 12, 36, 144, 720, 4320, 30240, 241920, 2177280, 21772800, 239500800, 2874009600, 37362124800, 523069747200, 7846046208000, 125536739328000, 2134124568576000, 38414242234368000, 729870602452992000, 14597412049059840000, 306545653030256640000

Offset: 0

Author

Vincenzo Librandi, Feb 13 2018

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300

Crossrefs

Cf. A274266.

Cf. sequences of the type k*n!: A000142 (k=1), A052849 (k=2), A052560 (k=3), A052578 (k=4), A052648 (k=5), this sequence (k=6), A062098 (k=7), A159038 (k=8), A174183 (k=10).

Programs

GAP

Concatenation([0], List([1..25], n -> 6*Factorial(n))); # Bruno Berselli, Feb 13 2018

Magma

[n eq 0 select 0 else 6*Factorial(n): n in [0..25]];

Mathematica

Join[{0}, 6 Range[25]!]

PARI

a(n) = if (n, 6*n!, 0); \\ Michel Marcus, Feb 15 2018

Formula

E.g.f.: 6*x/(1-x).

a(n) = n*a(n-1) = 6*A000142(n) for n>0.

Extensions

Edited by Bruno Berselli, Feb 13 2018