A097023 Numbers k such that the sum of the divisors of 2*k^2 is a square.

313, 335, 2612, 2817, 3015, 3820, 23508, 34380, 36647, 38193, 42217, 50281, 64972, 73535, 96404, 103180, 155991, 265364, 325847, 329823, 379953, 397068, 452529, 476545, 584748, 624748, 661815, 668660, 867636, 928620

Offset

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..200

Formula

a(n) = sqrt(A074388(n)/2). - Amiram Eldar, Aug 13 2024

Example

sigma(2*313^2) = 543^2.

Mathematica

Select[Range[950000], IntegerQ[Sqrt[DivisorSigma[1, 2#^2]]]&] (* Harvey P. Dale, Jul 10 2012 *)

Crossrefs

Cf. A000203, A008847, A074388, A097024.

Sequence in context: A083972 A045275 A238057 * A159574 A139656 A061323

Adjacent sequences: A097020 A097021 A097022 * A097024 A097025 A097026

Keyword

nonn

Author

Labos Elemer, Aug 24 2004

Extensions

Definition clarified by Harvey P. Dale, Jul 10 2012

Status

approved