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A085635
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Compute S, the number of different quadratic residues modulo B for every base B. If the density S/B is smaller for B than for every B' less than B, then B is added to the sequence.
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1
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2, 3, 4, 8, 12, 16, 32, 48, 80, 96, 112, 144, 240, 288, 336, 480, 560, 576, 720, 1008, 1440, 1680, 2016, 2640, 2880, 3600, 4032, 5040, 7920, 9360, 10080, 15840, 18480, 20160, 25200, 31680, 37440, 39600, 44352, 50400, 55440, 65520, 85680, 95760
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| After 2880, 3360 has exactly the same density (5%).
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EXAMPLE
| a(3)=4 because for B=4 the different quadratic residues are {0,1}, so S=2, the density is D_4=50%, that is smaller than D_2=100% and D_3=66,67%.
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PROG
| (PARI) r=0; for(n=1, 1e6, t=1-sum(k=1, n, issquare(Mod(k, n)))/n; if(t>r, r=t; print1(n", "))) \\ Charles R Greathouse IV, Jul 15 2011
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CROSSREFS
| Cf. A084848.
Sequence in context: A189375 A062923 A133464 * A013914 A060200 A057608
Adjacent sequences: A085632 A085633 A085634 * A085636 A085637 A085638
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KEYWORD
| nonn
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AUTHOR
| Jose R. Brox (tautocrona(AT)terra.es), Jul 10 2003
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EXTENSIONS
| More terms from Jud McCranie (JudMcCranie(AT)ugaalum.uga.edu), Jul 12 2003
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