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A008767 a(n) = floor(n/7)*ceiling(n/7). 1
0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 4, 6, 6, 6, 6, 6, 6, 9, 12, 12, 12, 12, 12, 12, 16, 20, 20, 20, 20, 20, 20, 25, 30, 30, 30, 30, 30, 30, 36, 42, 42, 42, 42, 42, 42, 49, 56, 56, 56, 56, 56, 56, 64, 72, 72, 72, 72, 72 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,9
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,2,-2,0,0,0,0,0,-1,1).
FORMULA
a(n) = +2*a(n-1) -2*a(n-2) +2*a(n-3) -2*a(n-4) +2*a(n-5) -2*a(n-7) +2*a(n-8) -2*a(n-9) +2*a(n-10) -2*a(n-11) +a(n-12). - R. J. Mathar, Mar 11 2012
a(0)=0, a(1)=0, a(2)=0, a(3)=0, a(4)=0, a(5)=0, a(6)=0, a(7)=1, a(8)=2, a(9)=2, a(10)=2, a(11)=2, a(12)=2, a(13)=2, a(14)=4, a(n) = a(n-1) +2*a(n-7) -2*a(n-8) -a(n-14) +a(n-15). - Harvey P. Dale, Aug 12 2012
MAPLE
seq(floor(n/7)*ceil(n/7), n=0..70); # G. C. Greubel, Sep 10 2019
MATHEMATICA
Table[Floor[n/7]Ceiling[n/7], {n, 0, 70}] (* Harvey P. Dale, Aug 12 2012 *)
PROG
(PARI) vector(70, n, ((n-1)\7)*ceil((n-1)/7) ) \\ G. C. Greubel, Sep 10 2019
(Magma) [Floor(n/7)*Ceiling(n/7): n in [0..70]]; // G. C. Greubel, Sep 10 2019
(Sage) [floor(n/7)*ceil(n/7) for n in (0..70)] # G. C. Greubel, Sep 10 2019
(GAP) a:=[0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 4];; for n in [16..70] do a[n]:= a[n-1]+2*a[n-7]-2*a[n-8]-a[n-14]+a[n-15]; od; a; # G. C. Greubel, Sep 10 2019
CROSSREFS
Sequence in context: A307616 A202709 A279611 * A244461 A366811 A343925
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 29 08:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)