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Search: id:A134427
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| A134427 |
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Numbers n such that n^2 + 1 is a composite square-free number. |
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+0
1
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| 3, 5, 8, 9, 11, 12, 13, 15, 17, 19, 21, 22, 23, 25, 27, 28, 29, 30, 31, 33, 34, 35, 37, 39, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 58, 59, 60, 61, 62, 63, 64, 65, 67, 69, 71, 72, 73, 75, 76, 77, 78, 79, 80, 81, 83, 85, 86, 87, 88, 89, 91, 92, 95, 96, 97, 98, 100, 101
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1)=3, because 3^2 + 1 = 10 is a composite square-free number,
a(2)=5, because 5^2 + 1 = 26 is a composite square-free number,
a(3)=8, becasue 8^2 + 1 = 50 is composite square-free.
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MAPLE
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ts_fn4:=proc(n) local i, tren, ans; ans:=[ ]: for i from 1 to n do tren := i^(2)+1: if (isprime(tren) = false and numtheory[mobius] (tren) <> 0 ) then ans:=[ op(ans), i ]: fi od: RETURN(ans) end: ts_fn4(200);
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CROSSREFS
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Cf. A002496, A124809.
Adjacent sequences: A134424 A134425 A134426 this_sequence A134428 A134429 A134430
Sequence in context: A077523 A107820 A064186 this_sequence A065347 A085722 A023980
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KEYWORD
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nonn
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AUTHOR
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Jani Melik (jani_melik(AT)hotmail.com), Jan 18 2008
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EXTENSIONS
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Definition corrected by T. D. Noe, Sep 16 2008
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