OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..400
Mircea Merca, Inequalities and Identities Involving Sums of Integer Functions J. Integer Sequences, Vol. 14 (2011), Article 11.9.1.
Index entries for linear recurrences with constant coefficients, signature (8,-8,8,-7).
FORMULA
a(n) = round((7*7^n-7)/60) = round((7*7^n+5)/60).
a(n) = floor((7*7^n+17)/60).
a(n) = ceiling((7*7^n-7)/60).
a(n) = a(n-4) + 40*7^(n-3), n > 3.
a(n) = 8*a(n-1) - 8*a(n-2) + 8*a(n-3) - 7*a(n-4), n > 3.
G.f.: -(2*x^2-x)/((x-1)*(7*x-1)*(x^2+1)).
EXAMPLE
a(4) = 0 + 1 + 5 + 34 + 240 = 280.
MAPLE
A178397 := proc(n) add( round(7^i/10), i=0..n) ; end proc:
MATHEMATICA
Accumulate[Floor[7^Range[0, 20]/10+1/2]] (* Harvey P. Dale, Aug 20 2011 *)
PROG
(Magma) [Round((7*7^n-7)/60): n in [0..40]]; // Vincenzo Librandi, Jun 23 2011
(PARI) a(n) = (7*7^n+17)\60; \\ Altug Alkan, Sep 21 2018
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Mircea Merca, Dec 28 2010
STATUS
approved