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Search: id:A047201
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| A047201 |
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Numbers that are congruent to {1, 2, 3, 4} mod 5. |
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+0
7
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| 1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 19, 21, 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, 34, 36, 37, 38, 39, 41, 42, 43, 44, 46, 47, 48, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 64, 66, 67, 68, 69, 71
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Numbers not divisible by 5. - Lekraj Beedassy (blekraj(AT)yahoo.com), Dec 17 2006
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]
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FORMULA
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G.f.: (x+2*x^2+3*x^3+4*x^4+4*x^5+3*x^6+2*x^7+x^8)/(1-x^4)^2 - Len Smiley (smiley(AT)math.uaa.alaska.edu)
a(n)=5+a(n-4).
G.f.: (1+x+x^2+x^3+x^4)/((1-x)*(1-x^4)).
a(n)=n-1+floor((n+3)/4) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
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PROGRAM
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(PARI) a(n)= 1+n+n\4
(Other) [i for i in range(72) if gcd(5, i) == 1] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 21 2009]
(PARI) a(n)=n-1+floor((n+3)/4) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
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CROSSREFS
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Cf. A045572.
Sequence in context: A001961 A020656 A039116 this_sequence A023721 A087066 A120518
Adjacent sequences: A047198 A047199 A047200 this_sequence A047202 A047203 A047204
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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