OFFSET
0,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..3300
Index entries for linear recurrences with constant coefficients, signature (4, -4).
FORMULA
a(n) = Sum_{k=0..n} (k+7)*binomial(n,k).
From R. J. Mathar, Apr 20 2009: (Start)
a(n) = (14+n)*2^(n-1).
a(n) = 4*a(n-1) - 4*a(n-2).
G.f.: (7-13*x)/(1-2x)^2. (End)
E.g.f.: (x+7)*exp(2*x). - G. C. Greubel, Jun 02 2018
From Amiram Eldar, Jan 19 2021: (Start)
Sum_{n>=0} 1/a(n) = 32768*log(2) - 204619418/9009.
Sum_{n>=0} (-1)^n/a(n) = 598484902/45045 - 32768*log(3/2). (End)
EXAMPLE
a(0)=7, a(1) = 2*7 + 1 = 15, a(2) = 2*15 + 2 = 32, a(3) = 2*32 + 4 = 68, a(4) = 2*68 + 8 = 144, ...
MATHEMATICA
LinearRecurrence[{4, -4}, {7, 15}, 30] (* or *) Table[(14+n)*2^(n-1), {n, 0, 30}] (* G. C. Greubel, Jun 02 2018 *)
nxt[{n_, a_}]:={n+1, 2a+2^n}; NestList[nxt, {0, 7}, 30][[All, 2]] (* Harvey P. Dale, Jan 01 2023 *)
PROG
(PARI) for(n=0, 30, print1((14+n)*2^(n-1), ", ")) \\ G. C. Greubel, Jun 02 2018
(Magma) [(14+n)*2^(n-1): n in [0..30]]; // G. C. Greubel, Jun 02 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Philippe Deléham, Apr 20 2009
EXTENSIONS
More terms from R. J. Mathar, Apr 20 2009
STATUS
approved