A166070 - OEIS

%I #11 Oct 02 2023 20:19:31

%S 1,2,3,5,6,7,11,13,17,19,23,28,29,31,37,41,43,47,53,59,61,67,71,73,79,

%T 83,89,97,101,103,107,109,113,120,127,131,137,139,149,151,157,163,167,

%U 173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263

%N Sorted sequence of primes and multiply perfect numbers.

%C Numbers k such that sigma(k) is divisible by all proper divisors of k.

%H Harvey P. Dale, <a href="/A166070/b166070.txt">Table of n, a(n) for n = 1..1000</a>

%F A000040 Union A007691.

%F {1} Union A053813 Union A166069.

%F {1} Union A000040 Union A000396 Union A166069.

%e a(4) = 6: all proper divisors of 6 (1, 2, 3) divide sigma(6) = 12.

%t Select[Range[300],And@@Divisible[DivisorSigma[1,#],Most[Divisors[#]]]&] (* _Harvey P. Dale_, Jan 18 2015 *)

%Y Cf. A053813.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Oct 06 2009, Oct 16 2009