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A147570
a(n) = phi(A020492(n)).
2
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
1,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (calculated from the b-file at A020492)
EXAMPLE
a(5) = phi(A020492(5)) = phi(12) = 4.
PROG
(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
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.
Sequence in context: A308841 A176528 A108891 * A049625 A202102 A300576
KEYWORD
easy,nonn
AUTHOR
Enoch Haga, Nov 07 2008
EXTENSIONS
Edited by Klaus Brockhaus, Nov 09 2008
STATUS
approved