login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A047391 Numbers that are congruent to {1, 3, 5} mod 7. 3
1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, 26, 29, 31, 33, 36, 38, 40, 43, 45, 47, 50, 52, 54, 57, 59, 61, 64, 66, 68, 71, 73, 75, 78, 80, 82, 85, 87, 89, 92, 94, 96, 99, 101, 103, 106, 108, 110, 113, 115, 117, 120, 122, 124, 127, 129, 131, 134, 136, 138, 141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

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

FORMULA

From Bruno Berselli, Mar 25 2011:  (Start)

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

a(n) = 7*floor((n-1)/3)+2*(n-1 mod 3)+1.

a(n) = (1/3)*(7*n-5-A049347(n)). (End)

From Wesley Ivan Hurt, Jun 13 2016: (Start)

a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.

a(n) = (21*n-15-3*cos(2*n*Pi/3)+sqrt(3)*sin(2*Pi*n/3))/9.

a(3k) = 7k-2, a(3k-1) = 7k-4, a(3k-2) = 7k-6. (End)

MAPLE

A047391:=n->(21*n-15-3*cos(2*n*Pi/3)+sqrt(3)*sin(2*Pi*n/3))/9: seq(A047391(n), n=1..100); # Wesley Ivan Hurt, Jun 13 2016

MATHEMATICA

Select[Range[0, 150], MemberQ[{1, 3, 5}, Mod[#, 7]] &] (* Wesley Ivan Hurt, Jun 13 2016 *)

LinearRecurrence[{1, 0, 1, -1}, {1, 3, 5, 8}, 100] (* Vincenzo Librandi, Jun 14 2016 *)

PROG

(MAGMA) [n: n in [1..122] | n mod 7 in [1, 3, 5]]; // Bruno Berselli, Mar 25 2011

CROSSREFS

Cf. A049347.

Sequence in context: A184584 A191160 A189929 * A184655 A090846 A195170

Adjacent sequences:  A047388 A047389 A047390 * A047392 A047393 A047394

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 6 08:53 EST 2016. Contains 278775 sequences.