|
| |
|
|
A047304
|
|
Numbers not divisible by 7.
|
|
7
| |
|
|
1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 57, 58, 59, 60, 61, 62, 64, 65, 66
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Numbers that are congruent to {1, 2, 3, 4, 5, 6} mod 7. Different from A020658.
More generally the sequence of numbers not divisible by some fixed integer m>=2 is given by a(n,m)=n-1+floor((n+m-2)/(m-1)). [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
Complement of A008589; A109720(a(n))=1; A082784(a(n))=0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 30 2009]
|
|
|
LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,0,0,0,0,1,-1).
|
|
|
FORMULA
| a(n)=n-1+floor((n+5)/6) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
G.f. x*(1+x+x^2+x^3+x^4+x^5+x^6) / ( (1+x)*(1+x+x^2)*(x^2-x+1)*(x-1)^2 ). - R. J. Mathar, Oct 08 2011
|
|
|
MATHEMATICA
| Select[Table[n, {n, 200}], Mod[#, 7]!=0&] (*From Vladimir Joseph Stephan Orlovsky, Feb 18 2011*)
|
|
|
PROG
| (Other) sage: [i for i in range(67) if gcd(7, i) == 1] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 21 2009]
(PARI) a(n)=n-1+floor((n+5)/6) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
|
|
|
CROSSREFS
| Sequence in context: A172251 A187396 A020659 * A020658 A195178 A043092
Adjacent sequences: A047301 A047302 A047303 * A047305 A047306 A047307
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
|
| |
|
|
