OFFSET
10,1
COMMENTS
10! seconds = 6 weeks (exactly)
11! seconds = 66 weeks (exactly)
12! seconds = 792 weeks (exactly), etc.
Demonstration of first term:
6 w * 7 d/w * 24 h/d * 60 m/h * 60 s/m = seconds in 6 weeks =
(2*3)*(1*7) *(3*8) * (6*10) * (3*5*4) =
1*2*3*4*5*6*7*8*(3^2)*10 = 10! seconds
LINKS
Brady Haran, James Grime, 10!, Numberphile video (2012)
FORMULA
a(n) = 6*n!/10!.
a(n) = 6*A051431(n-10), for n>=10.
EXAMPLE
For n=12, a(12) = 6*(12)!/10! = 792; interpretation: 12! seconds = 792 weeks.
MATHEMATICA
f[n_] := n!/(60*60*24*7); Array[f, 17, 10] (* Robert G. Wilson v, Jan 12 2016 *)
PROG
(PARI) a(n) = 6*n!/10!; \\ Altug Alkan, Jan 12 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard H. Sweetman, Jan 10 2016
STATUS
approved