OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 188
Brian O'Sullivan and Thomas Busch, Spontaneous emission in ultra-cold spin-polarised anisotropic Fermi seas, arXiv 0810.0231v1 [quant-ph], 2008. [Eq 8a, lambda=5]
Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,1,-2,1).
FORMULA
a(n) = floor( (n+3)*(n+4)/10 ) = (n+2)*(n+5)/10 + b(n)/5 where b(n) = A010891(n-2) + 2*A092202(n-1) = 0, 1, 1, 0, -2, ... with period length 5.
G.f.: 1/((1-x)^2*(1-x^5)).
a(n) = a(n-5) + n + 1. - Paul Barry, Jul 14 2004
From Mitch Harris, Sep 08 2008: (Start)
a(n) = Sum_{j=0..n+5} floor(j/5).
a(n-5) = (1/2)floor(n/5)*(2*n - 3 - 5*floor(n/5)). (End)
a(n) = A130520(n+5). - Philippe Deléham, Apr 05 2013
EXAMPLE
From Philippe Deléham, Apr 05 2013: (Start)
Stored in five columns:
1 2 3 4 5
7 9 11 13 15
18 21 24 27 30
34 38 42 46 50
55 60 65 70 75
81 87 93 99 105
112 119 126 133 140
(End)
MAPLE
MATHEMATICA
LinearRecurrence[{2, -1, 0, 0, 1, -2, 1}, {1, 2, 3, 4, 5, 7, 9}, 50] (* Jean-François Alcover, Jan 18 2018 *)
PROG
(Magma) [Floor((n+3)*(n+4)/10): n in [0..50] ]; // Vincenzo Librandi, Aug 21 2011
(PARI) a(n)=(n+3)*(n+4)\10 \\ Charles R Greathouse IV, Oct 07 2015
(Sage) [floor((n+3)*(n+4)/10) for n in (0..50)] # G. C. Greubel, Jul 30 2019
(GAP) List([0..50], n-> Int((n+3)*(n+4)/10)); # G. C. Greubel, Jul 30 2019
CROSSREFS
KEYWORD
nonn,easy,tabf
AUTHOR
STATUS
approved