A157848 Corresponding values of arithmetic means of divisors of numbers from A007340.

1, 3, 28, 45, 84, 182, 270, 620, 546, 1240, 1330, 1638, 1260, 1365, 2660, 8128, 6200, 6200, 6944, 8190, 9310, 7560, 8190, 18600, 15120, 18620, 16380, 25935, 30240, 32760, 63700, 55860, 40950, 55800, 117800, 98208, 105664, 117800, 121030, 173600, 167400, 155610

Offset

1,2

Comments

A007340 = numbers k such that the arithmetic mean of divisors of k is integer and equal to one of the divisors of this numbers.

Links

Amiram Eldar, Table of n, a(n) for n = 1..847 (calculated from the b-file at A007340)

Formula

a(n) = sigma(A007340(n))/tau(A007340(n)) = A000203((A007340(n))/A000005(A007340(n)).

Example

a(3) = 28, because 28 is arithmetic mean of divisors of A007340(3)=140 and also is divisor of 140.

Prog

[SumOfDivisors(n) / NumberOfDivisors(n): n in[A007340(n)] ]
(PARI) lista(kmax) = {my(f, s, d); for(k = 1, kmax, f = factor(k); s = sigma(f); d = numdiv(f); if(!(s % d) && denominator(d / sigma(f, -1)) == 1, print1(s/d, ", "))); } \\ Amiram Eldar, Apr 15 2024

Crossrefs

Cf. A000203, A007340, A000005.

Sequence in context: A037102 A042169 A041785 * A225674 A253653 A267360

Adjacent sequences: A157845 A157846 A157847 * A157849 A157850 A157851

Keyword

nonn,changed

Author

Jaroslav Krizek, Mar 07 2009, Mar 09 2009

Extensions

Corrected and extended by Jaroslav Krizek, Mar 29 2015

Status

approved