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A042968
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Not divisible by 4.
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30
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1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 45, 46, 47, 49, 50, 51, 53, 54, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95, 97, 98, 99, 101, 102
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| A064680(A064680(a(n))) = a(n) - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 19 2001
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]
Also a(n,m)=floor((m*n-1)/(m-1))[From Gary Detlefs (gdetlefs(AT)aol.com), May 14 2011]
Numbers having not more even than odd divisors: A048272(a(n)) >= 0. [Reinhard Zumkeller, Jan 21 2012]
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,0,1,-1).
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FORMULA
| a(n) = +1*a(n-1) +1*a(n-3) -1*a(n-4).
a(n) = 4 + a(n-3).
G.f.: (1+x)*(1+x^2) / ( (1+x+x^2)*(x-1)^2 )- Michael Somos Jan 12 2000.
Nearest integer to sum(k>n, 1/k^4)/sum(k>n, 1/k^5) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 12 2003
a(n)=n-1+floor((n+2)/3) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
a(n)=floor((4*n-1)/3). [From Gary Detlefs (gdetlefs(AT)aol.com), May 14 2011]
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MATHEMATICA
| Select[Table[n, {n, 200}], Mod[#, 4]!=0&] (*From Vladimir Joseph Stephan Orlovsky, Feb 18 2011*)
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PROG
| (PARI) a(n)=1+n+n\3
(PARI) a(n)=n-1+floor((n+2)/3) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 11 2009]
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CROSSREFS
| Cf. A001651.
Sequence in context: A039053 A059557 A195291 * A048103 A193303 A092418
Adjacent sequences: A042965 A042966 A042967 * A042969 A042970 A042971
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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