The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A291459 Numbers n having a proper divisor d such that sigma(n) - k*d = k*n. Case k = 5. 2

%I

%S 294053760,575134560,739458720,882161280,1193512320,1314593280,

%T 1725403680,2539555200,2588105520,2646483840,2711348640,3008396160,

%U 3891888000,4053329280,4214770560,4648644000,4802878080,5176211040,5194949760,5258373120,6470263800,6768891360,7900532640

%N Numbers n having a proper divisor d such that sigma(n) - k*d = k*n. Case k = 5.

%C Case k=2 are the admirable numbers (A111592).

%C Subset of A215264.

%e One of the proper divisors of 294053760 is 2056320 and sigma(294053760) - 5*2056320 = 1480550400 - 10281600 = 1470268800 = 5*294053760.

%e One of the proper divisors of 3891888000 is 314496 and sigma(3891888000) - 5*314496 = 19461012480 - 1572480 = 19459440000 = 5*3891888000.

%p with(numtheory): P:=proc(q,h) local a,k,n; for n from 1 to q do a:=sort([op(divisors(n))]);

%p for k from 1 to nops(a)-1 do if sigma(n)-h*a[k]=h*n then print(n); break; fi; od; od; end: P(10^10,5);

%Y Cf. A000203, A111592, A215264, A291457, A291458.

%K nonn,easy

%O 1,1

%A _Paolo P. Lava_, Aug 24 2017

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 11 20:13 EDT 2022. Contains 356067 sequences. (Running on oeis4.)