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A047327 Numbers that are congruent to {3, 5, 6} mod 7. 1
3, 5, 6, 10, 12, 13, 17, 19, 20, 24, 26, 27, 31, 33, 34, 38, 40, 41, 45, 47, 48, 52, 54, 55, 59, 61, 62, 66, 68, 69, 73, 75, 76, 80, 82, 83, 87, 89, 90, 94, 96, 97, 101, 103, 104, 108, 110, 111, 115, 117, 118, 122, 124, 125, 129, 131, 132, 136, 138, 139, 143 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also, numbers k such that (k^3+1)/7 is a nonnegative integer. - Bruno Berselli, Jan 16 2016

LINKS

Table of n, a(n) for n=1..61.

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

FORMULA

G.f.: x*(3+2*x+x^2+x^3)/((1+x+x^2)*(x-1)^2). - R. J. Mathar, Dec 04 2011

From Wesley Ivan Hurt, Jun 07 2016: (Start)

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

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

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

MAPLE

A047327:=n->(21*n-9*cos(2*n*Pi/3)+sqrt(3)*sin(2*n*Pi/3))/9: seq(A047327(n), n=1..100); # Wesley Ivan Hurt, Jun 07 2016

MATHEMATICA

Select[Range[0, 150], MemberQ[{3, 5, 6}, Mod[#, 7]] &] (* Wesley Ivan Hurt, Jun 07 2016 *)

PROG

(MAGMA) [n : n in [0..150] | n mod 7 in [3, 5, 6]]; // Wesley Ivan Hurt, Jun 07 2016

CROSSREFS

Sequence in context: A072282 A028727 A257346 * A028927 A099190 A122772

Adjacent sequences:  A047324 A047325 A047326 * A047328 A047329 A047330

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified October 24 09:38 EDT 2021. Contains 348225 sequences. (Running on oeis4.)