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A011884 Floor(n(n - 1)/31). 1
0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 45, 47, 50, 52, 55, 58, 61, 63, 66, 69, 72, 75, 79, 82, 85, 88, 92, 95, 99, 102, 106, 110, 114, 118, 122, 126, 130, 134, 138, 142, 146, 151, 155, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,10

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1).

FORMULA

G.f.: -((x^7 (1+x^5-2 x^7+x^9+x^14) (1+(-1+x) x (1+(-1+x) x) (1+x+x^2)))/(-1+x (2+x (-1+(-1+x)^2 x^29)))). - Peter J. C. Moses, Jun 01 2014

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)=1, a(9)=2, a(10)=2, a(11)=3, a(12)=4, a(13)=5, a(14)=5, a(15)=6, a(16)=7, a(17)=8, a(18)=9, a(19)=11, a(20)=12, a(21)=13, a(22)=14, a(23)=16, a(24)=17, a(25)=19, a(26)=20, a(27)=22, a(28)=24, a(29)=26, a(30)=28, a(31)=30, a(32)=32, a(n)=2*a(n-1)-a(n-2)+a(n-31)- 2*a(n-32)+ a(n-33). - Harvey P. Dale, Jan 23 2016

EXAMPLE

a(11) = 3 because 11 * 10/31 = 3.548387...

a(12) = 4 because 12 * 11/31 = 4.258...

a(13) = 5 because 13 * 12/31 = 5.032258...

MAPLE

A011884:=n->floor(n*(n-1)/31); seq(A011884(n), n=0..50); # Wesley Ivan Hurt, Jun 01 2014

MATHEMATICA

Table[Floor[n(n - 1)/31], {n, 0, 79}] (* Alonso del Arte, Apr 13 2014 *)

CoefficientList[Series[-((x^7 (1 + x^5 - 2 x^7 + x^9 + x^14) (1 + (-1 + x) x (1 + (-1 + x) x) (1 + x + x^2)))/(-1 + x (2 + x (-1 + (-1 + x)^2 x^29)))), {x, 0, 100}], x] (* Vincenzo Librandi, Jun 02 2014 *)

LinearRecurrence[{2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1}, {0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19, 20, 22, 24, 26, 28, 30, 32}, 80] (* Harvey P. Dale, Jan 23 2016 *)

PROG

(MAGMA) [Floor(n*(n-1)/31): n in [0..50]]; // Wesley Ivan Hurt, Jun 01 2014

CROSSREFS

Sequence in context: A127037 A089646 A241730 * A029070 A112341 A242774

Adjacent sequences:  A011881 A011882 A011883 * A011885 A011886 A011887

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Dec 11 1996

STATUS

approved

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Last modified April 6 10:28 EDT 2020. Contains 333273 sequences. (Running on oeis4.)