OFFSET
1,2
LINKS
FORMULA
7*a(n) = (7*n)(!^7) = Product_{j=1..n} 7*j = 7^n*n!.
E.g.f.: x/(1-7*x).
a(n) = A051188(n)/7.
From Amiram Eldar, Jan 08 2022: (Start)
Sum_{n>=1} 1/a(n) = 7*(exp(1/7)-1).
Sum_{n>=1} (-1)^(n+1)/a(n) = 7*(1-exp(-1/7)). (End)
MATHEMATICA
Table[7^(n-1)*n!, {n, 1, 30}] (* or *) Drop[With[{nn = 50}, CoefficientList[ Series[x/(1-7*x), {x, 0, nn}], x]*Range[0, nn]!], 1] (* G. C. Greubel, Feb 22 2018 *)
PROG
(PARI) my(x='x+O('x^30)); Vec(serlaplace(x/(1-7*x))) \\ G. C. Greubel, Feb 22 2018
(Magma) [7^(n-1)*Factorial(n): n in [1..30]]; // G. C. Greubel, Feb 22 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
EXTENSIONS
More terms from G. C. Greubel, Feb 22 2018
STATUS
approved