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A038179
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Result of second stage of sieve of Eratosthenes.
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9
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2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, 61, 65, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97, 101, 103, 107, 109, 113, 115, 119, 121, 125, 127, 131, 133, 137, 139, 143, 145, 149, 151
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Terms of this sequence (starting from the second term) are equal to the result of the expression sqrt(4!*(k+1) + 1) - but only when this expression yields integral values (that is when the parameter k takes values, which are terms of A144065) [From Alexander R. Povolotsky (pevnev(AT)juno.com), Sep 09 2008]
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REFERENCES
| F. S. Roberts, Applied Combinatorics, Prentice-Hall, 1984, p. 256.
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LINKS
| H. B. Meyer, Eratosthenes' sieve
Index entries for sequences generated by sieves
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FORMULA
| 2, 3 and numbers of the form 6m+-1. Apart from first two terms, same as A007310.
O.g.f.: x(2+x+x^3+2x^4)/((1+x)(1-x)^2). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2008
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MATHEMATICA
| Join[{2, 3}, Select[Table[n, {n, 2, 200}], Mod[#, 2]!=0&&Mod[#, 3]!=0&]] (*From Vladimir Joseph Stephan Orlovsky, Feb 18 2011*)
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PROG
| (PARI) The following PARI program applies to generate all terms besides first one: j=[]; for(n=0, 1000, if((floor(sqrt(4!*(n+1) + 1))) == ceil(sqrt(4!*(n+1) + 1)), j=concat(j, floor(sqrt(4!*(n+1) + 1))))); j [From Alexander R. Povolotsky (pevnev(AT)juno.com), Sep 09 2008]
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CROSSREFS
| Cf. A004280, A007310.
A144065 [From Alexander R. Povolotsky (pevnev(AT)juno.com), Sep 09 2008]
Sequence in context: A117322 A048380 A048382 * A192489 A161578 A186891
Adjacent sequences: A038176 A038177 A038178 * A038180 A038181 A038182
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KEYWORD
| easy,nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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