OFFSET
3,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 3..1000
P. A. MacMahon, The divisors of numbers, Proc. London Math. Soc., (2) 19 (1920), 305-340; Coll. Papers II, pp. 267-302.
Index entries for linear recurrences with constant coefficients, signature (14,-75,196,-263,174,-45).
FORMULA
a(n) = 5^(n-1) - n*3^(n-1) + n*(n-1)/2. - Ralf Stephan, May 08 2004
G.f.: x^3*(1 + 9*x - 17*x^2 - 9*x^3) / ((1-x)^3*(1-3*x)^2*(1-5*x)). - Colin Barker, Dec 19 2012
From Wolfdieter Lang, Apr 17 2017: (Start)
a(n) = A060187(n, 3) , n >= 3 (and 0 for n = 0,1,2).
a(n) = A060187(n, n-2), n >= 3 (and 0 for n = 0,1,2).
E.g.f.: (2*exp(5*x) - 10*x*exp(3*x) + 5*x^2*exp(x) - 2)/10. (End)
MATHEMATICA
Table[5^(n-1) -n*3^(n-1) +n*(n-1)/2, {n, 3, 40}] (* G. C. Greubel, Jul 31 2024 *)
PROG
(Magma)
[5^(n-1) -n*3^(n-1) +n*(n-1)/2: n in [3..40]]; // G. C. Greubel, Jul 31 2024
(SageMath)
[5^(n-1) -n*3^(n-1) +n*(n-1)//2 for n in range(3, 41)] # G. C. Greubel, Jul 31 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 20 2001
EXTENSIONS
More terms from Vladeta Jovovic, Mar 20 2001
STATUS
approved