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%I #24 Jan 16 2018 02:37:44
%S 1,2,3,6,12,14,15,30,35,42,56,70,78,105,140,168,190,210,248,264,270,
%T 295,357,418,420,570,590,594,616,630,714,744,767,812,840,885,910,1038,
%U 1045,1240,1254,1416,1485,1534,1589,1672,1770,1848,2065,2090,2214,2301,2376,2422,2436,2580,2730,2970
%N Numbers n such that phi(n) | sigma_7(n).
%C sigma_7(n) is the sum of the 7th powers of the divisors of n.
%C In contrast to other values of k for which sigma_k(n) is much less frequently divisible by phi(n) (cf. A015762 (k=4: a(7) > 10^11 if it exists), A015759 (k=2: a(23) > 10^11)), it is quite easy to compute hundreds or even thousands of terms of the present sequence. - _M. F. Hasler_, Aug 26 2017
%H M. F. Hasler, <a href="/A015765/b015765.txt">Table of n, a(n) for n = 1..10000</a> (first 1001 terms from Vincenzo Librandi)
%t Select[Range[2100],Divisible[DivisorSigma[7,#],EulerPhi[#]]&] (* _Harvey P. Dale_, Aug 17 2013 *)
%o (PARI) select( is(n)=sigma(n,7)%eulerphi(n)==0, [1..3000]) \\ _M. F. Hasler_, Aug 26 2017
%K nonn,easy
%O 1,2
%A _Robert G. Wilson v_
%E Third line of data completed by _M. F. Hasler_, Aug 26 2017