login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A303996 Numbers whose sum of divisors is the sixth power of one of their divisors. 6
1, 17490, 19410, 22578, 2823492, 162523452, 165982908, 216731788, 221416468, 221940628, 226768440, 230365560, 232815480, 234896520, 238942920, 240737160, 241362120, 242067720, 242454120, 242655720, 258182910, 264254670, 268298190, 272819070, 277297710, 286008510 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Subset of A019424.

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

Divisors of 17490 are 1, 2, 3, 5, 6, 10, 11, 15, 22, 30, 33, 53, 55, 66, 106, 110, 159, 165, 265, 318, 330, 530, 583, 795, 1166, 1590, 1749, 2915, 3498, 5830, 8745, 17490 and their sum is 46656 = 6^6.

MAPLE

with(numtheory): P:=proc(q) local a, k, n;

for n from 1 to q do a:=sort([op(divisors(n))]);

for k from 1 to nops(a) do if sigma(n)=a[k]^6 then print(n); break; fi; od; od; end: P(10^9);

PROG

(PARI) isok(n) = (n==1) || (ispower(s=sigma(n), 6) && !(n % sqrtnint(s, 6))); \\ Michel Marcus, May 05 2018

CROSSREFS

Cf. A000203, A019424, A303123, A303993, A303994, A303995.

Sequence in context: A043875 A236806 A048256 * A251641 A251638 A234562

Adjacent sequences:  A303993 A303994 A303995 * A303997 A303998 A303999

KEYWORD

nonn,easy

AUTHOR

Paolo P. Lava, May 04 2018

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 30 15:42 EDT 2020. Contains 333127 sequences. (Running on oeis4.)