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A051188 Sept-factorial numbers. 18
1, 7, 98, 2058, 57624, 2016840, 84707280, 4150656720, 232436776320, 14643516908160, 1025046183571200, 78928556134982400, 6629998715338521600, 603329883095805465600, 59126328543388935628800 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
For n >= 1, a(n) is the order of the wreath product of the symmetric group S_n and the Abelian group (C_7)^n. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 07 2001
LINKS
FORMULA
a(n) = n!*7^n =: (7*n)(!^7).
a(n) = 7*A034834(n) = Product_{k=1..n} 7*k, n >= 1.
E.g.f.: 1/(1 - 7*x).
G.f.: 1/(1 - 7*x/(1 - 7*x/(1 - 14*x/(1 - 14*x/(1 - 21*x/(1 - 21*x/(1 - 28*x/(1 - 28*x/(1 - ... (continued fraction). - Philippe Deléham, Jan 08 2012
From Amiram Eldar, Jun 25 2020: (Start)
Sum_{n>=0) 1/a(n) = e^(1/7) (A092516).
Sum_{n>=0) (-1)^n/a(n) = e^(-1/7) (A092750). (End)
PROG
(Magma) [7^n*Factorial(n): n in [0..20]]; // Vincenzo Librandi, Oct 05 2011
(PARI) a(n) = n!*7^n; \\ Michel Marcus, Jun 08 2020
CROSSREFS
Sequence in context: A237022 A156266 A234873 * A367138 A113134 A334722
KEYWORD
easy,nonn
AUTHOR
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)