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A102531 Real part of absolute Gaussian perfect numbers, in order of increasing magnitude. See A102532 for the imaginary part. 4
3, 15, 6, 19, 111, 91, 159, 72, 472, 904, 2584, 1616, 999, 4328, 702, 4424, 7048, 7328, 2474, 9352, 7144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

An absolute Gaussian perfect number z satisfies abs(sigma(z)-z) = abs(z), where sigma(z) is sum of the divisors of z, as defined by Spira for Gaussian integers.

LINKS

Table of n, a(n) for n=1..21.

R. Spira, The Complex Sum Of Divisors, American Mathematical Monthly, 1961 Vol. 68, pp. 120-124.

EXAMPLE

For z=3+7i, we have sigma(z)-z = 7+3i, which has the same magnitude as z.

MATHEMATICA

lst={}; nn=1000; Do[z=a+b*I; If[Abs[z]<=nn && Abs[(DivisorSigma[1, z]-z)] == Abs[z], AppendTo[lst, {Abs[z]^2, z}]], {a, nn}, {b, nn}]; Re[Transpose[Sort[lst]][[2]]]

CROSSREFS

Cf. A102506 and A102507 (Gaussian multiperfect numbers). See also A101366, A101367.

Sequence in context: A248031 A066832 A102777 * A135546 A138006 A256557

Adjacent sequences:  A102528 A102529 A102530 * A102532 A102533 A102534

KEYWORD

nonn,more

AUTHOR

T. D. Noe, Jan 13 2005

STATUS

approved

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Last modified August 21 05:40 EDT 2019. Contains 326162 sequences. (Running on oeis4.)