cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A262359 Numbers k such that denominator(sigma(k)/k) = 6.

Original entry on oeis.org

18, 22932, 14520576, 1610563584, 1907020800, 2836487808, 6399679104, 70912195200, 82819376640, 159991977600, 2732372020224, 6164773235712, 68309300505600, 148068998977536, 154119330892800, 264727305267840, 649657533767040, 3701724974438400, 42503412523106304, 220312341220608000
Offset: 1

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Author

Michel Marcus, Sep 19 2015

Keywords

Examples

			sigma(18)/18 = 13/6, hence 18 is a term.
		

Crossrefs

Cf. similar sequences with A017666(n)=k: A159907 (k=2), A245775 (k=3), A229088 (k=4), A067237 (k=5).
Cf. A000203.

Programs

  • PARI
    isok(n) = denominator(sigma(n, -1)) == 6;
    
  • PARI
    lista(nn) = {k = 6; nb = 0; while (nb != nn, if (denominator(sigma(k,-1)) == 6, print1(k, ", "); nb++); k += 6;);}

Extensions

a(10)-a(12) from Jud McCranie, Oct 14 2023
More terms from David A. Corneth, Oct 15 2023
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