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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A147570 a(n) = phi(A020492(n)).

Original entry on oeis.org

1, 1, 2, 2, 4, 6, 8, 8, 24, 12, 24, 24, 24, 48, 48, 48, 72, 48, 120, 80, 72, 192, 180, 96, 144, 180, 240, 144, 192, 240, 336, 192, 288, 720, 480, 360, 720, 720, 480, 720, 720, 720, 672, 672, 576, 720, 960, 1440, 1872, 1680, 960, 1120, 1848, 2016, 1440, 1728, 1440
Offset: 1

Views

Author

Enoch Haga, Nov 07 2008

Keywords

Examples

			a(5) = phi(A020492(5)) = phi(12) = 4.
		

Crossrefs

Cf. A000010 (Euler totient function phi(n)), A000203 (sigma(n), sum of divisors of n), A020492 (balanced numbers, numbers n such that phi(n) divides sigma(n)), A023897 (sigma(n) / phi(n) for balanced numbers), A147569.

Programs

  • Magma
    [ a: n in [1..3500] | SumOfDivisors(n) mod a eq 0 where a is EulerPhi(n) ]; // Klaus Brockhaus, Nov 09 2008
    
  • PARI
    {for(n=1, 5000, a=eulerphi(n); if(sigma(n)%a==0, print1(a, ",")))} \\ Klaus Brockhaus, Nov 09 2008

Extensions

Edited by Klaus Brockhaus, Nov 09 2008
Showing 1-1 of 1 results.