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A334020 Numbers k such that s(k) = s(k+1), where s(k) is the sum of unitary divisors of k that are smaller than sqrt(k) (A334019). 4
2, 3, 4, 7, 8, 16, 31, 127, 186, 256, 318, 434, 473, 574, 582, 588, 730, 735, 819, 978, 1245, 1357, 1374, 1397, 1420, 1421, 1500, 1506, 1661, 1694, 1902, 1956, 1988, 2059, 2085, 2147, 2166, 2329, 2453, 2505, 2506, 2534, 2754, 2770, 2868, 2954, 2988, 3345, 3377 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

2 is a term since A334019(2) = A334019(3) = 1.

MATHEMATICA

s[n_] := DivisorSum[n, # &, #^2 < n && CoprimeQ[#, n/#] &]; Select[Range[3000], s[#] == s[# + 1] &]

CROSSREFS

Cf. A064125, A324295, A334019,

Sequence in context: A333801 A239973 A281782 * A006549 A134459 A225211

Adjacent sequences:  A334017 A334018 A334019 * A334021 A334022 A334023

KEYWORD

nonn

AUTHOR

Amiram Eldar, Apr 12 2020

STATUS

approved

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Last modified April 11 14:58 EDT 2021. Contains 342886 sequences. (Running on oeis4.)