login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130483 a(n) = Sum_{k=0..n} (k mod 5) (Partial sums of A010874). 26
0, 1, 3, 6, 10, 10, 11, 13, 16, 20, 20, 21, 23, 26, 30, 30, 31, 33, 36, 40, 40, 41, 43, 46, 50, 50, 51, 53, 56, 60, 60, 61, 63, 66, 70, 70, 71, 73, 76, 80, 80, 81, 83, 86, 90, 90, 91, 93, 96, 100, 100, 101, 103, 106, 110, 110, 111, 113, 116, 120, 120, 121, 123, 126, 130, 130 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Let A be the Hessenberg n X n matrix defined by: A[1,j]=j mod 5, A[i,i]=1, A[i,i-1]=-1. Then, for n>=1, a(n)=det(A). - Milan Janjic, Jan 24 2010

LINKS

Shawn A. Broyles, Table of n, a(n) for n = 0..1000

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

FORMULA

a(n) = 10*floor(n/5) + A010874(n)*(A010874(n)+1)/2.

G.f.: x*(1 + 2*x + 3*x^2 + 4*x^3)/((1-x^5)*(1-x)).

From Wesley Ivan Hurt, Jul 23 2016: (Start)

a(n) = a(n-5) - a(n-6) for n>5; a(n) = a(n-5) + 10 for n>4.

a(n) = 10 + Sum_{k=1..4} k*floor((n-k)/5). (End)

MAPLE

seq(coeff(series(x*(1+2*x+3*x^2+4*x^3)/((1-x^5)*(1-x)), x, n+1), x, n), n = 0..70); # G. C. Greubel, Aug 31 2019

MATHEMATICA

Accumulate[Mod[Range[0, 70], 5]] (* or *) Accumulate[PadRight[{}, 70, {0, 1, 2, 3, 4}]] (* Harvey P. Dale, Nov 11 2016 *)

PROG

(PARI) a(n) = sum(k=0, n, k % 5); \\ Michel Marcus, Apr 28 2018

(MAGMA) I:=[0, 1, 3, 6, 10, 10]; [n le 6 select I[n] else Self(n-1) + Self(n-5) - Self(n-6): n in [1..71]]; // G. C. Greubel, Aug 31 2019

(Sage)

def A130483_list(prec):

    P.<x> = PowerSeriesRing(ZZ, prec)

    return P(x*(1+2*x+3*x^2+4*x^3)/((1-x^5)*(1-x))).list()

A130483_list(70) # G. C. Greubel, Aug 31 2019

(GAP) a:=[0, 1, 3, 6, 10, 10];; for n in [7..71] do a[n]:=a[n-1]+a[n-5]-a[n-6]; od; a; # G. C. Greubel, Aug 31 2019

CROSSREFS

Cf. A010872, A010873, A010875, A010876, A010877, A130481, A130482, A130484, A130485.

Sequence in context: A198467 A198456 A032570 * A115012 A200723 A135738

Adjacent sequences:  A130480 A130481 A130482 * A130484 A130485 A130486

KEYWORD

nonn,easy

AUTHOR

Hieronymus Fischer, May 29 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 6 16:55 EDT 2020. Contains 335478 sequences. (Running on oeis4.)