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!)
A332478 Number that are unitary norm-multiply-perfect numbers in Gaussian integers. 0
1, 10, 12, 20160, 15713280, 137592000, 44289146880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that their norm of sum of unitary divisors in Gaussian integers, A332474(k), is divisible by their norm, k^2.

The corresponding ratios A332474(a(n))/(a(n)^2) are 1, 4, 1, 5, 5, 2, 5.

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

10 is a term since its sum of unitary divisors in Gaussian integers is -12 + 16*i, whose norm (-12)^2 + 16^2 = 400 is divisible by 10^2 = 100.

MATHEMATICA

f[p_, e_] := If[Abs[p] == 1, 1, (p^e + 1)]; Select[Range[21000], Divisible[Abs[ Times @@ f @@@ FactorInteger[#, GaussianIntegers -> True]]^2, #^2] &]

CROSSREFS

Cf. A002827, A327158, A332318, A332319, A332474.

Sequence in context: A255534 A262422 A248336 * A144814 A241174 A092887

Adjacent sequences:  A332475 A332476 A332477 * A332479 A332480 A332481

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, Feb 13 2020

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 September 23 09:03 EDT 2020. Contains 337298 sequences. (Running on oeis4.)