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A293183 Numbers n such that bsigma(n) = bsigma(n+1), where bsigma(n) is the sum of the bi-unitary divisors of n (A188999). 7
14, 27, 44, 459, 620, 957, 1334, 1634, 1652, 2204, 2685, 3195, 3451, 3956, 5547, 8636, 8907, 9844, 11515, 11745, 16874, 19491, 20145, 20155, 27643, 31724, 33998, 38180, 41265, 41547, 42818, 45716, 48364, 64665, 74875, 74918, 79316, 79826, 79833, 83780, 84134 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..2148 (terms below 2*10^10)

EXAMPLE

14 is in the sequence since bsigma(14) = bsigma(15) = 24.

MATHEMATICA

f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bsigma[m_] :=

DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; a = {}; b1 = 0; Do[b2 = bsigma[k]; If[b1 == b2, a = AppendTo[a, k - 1]]; b1 = b2, {k, 1, 10^6}]; a (* after Michael De Vlieger at A188999 *)

CROSSREFS

Cf. A002961, A064125, A188999.

Sequence in context: A086451 A190991 A306985 * A168596 A275251 A192354

Adjacent sequences:  A293180 A293181 A293182 * A293184 A293185 A293186

KEYWORD

nonn

AUTHOR

Amiram Eldar, Oct 01 2017

STATUS

approved

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Last modified September 17 19:02 EDT 2019. Contains 327137 sequences. (Running on oeis4.)