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A292986 Bi-unitary weird numbers: bi-unitary abundant numbers (A292982) that are not bi-unitary pseudoperfect (A292985). 4
70, 4030, 5390, 5830, 7192, 7400, 7912, 9272, 10430, 10570, 10792, 10990, 11410, 11690, 11830, 12110, 12530, 12670, 13370, 13510, 13790, 13930, 14770, 15610, 15890, 16030, 16310, 16730, 16870, 17272, 17570, 17990, 18410, 18830, 18970, 19390, 19670, 19810 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Analogous to weird numbers (A006037) with bi-unitary sigma (A188999) instead of sigma (A000203).

LINKS

Table of n, a(n) for n=1..38.

MATHEMATICA

f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bdiv[m_] := Select[Divisors[m], Last@Intersection[f@#, f[m/#]] == 1 &]; bsigma[m_] := DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; bAbundantQ[n_] := bsigma[n] > 2 n; a = {}; n = 0; While[Length[a] < 5, n++; If[!bAbundantQ[n], Continue[]]; d = Most[bdiv[n]]; c = SeriesCoefficient[Series[Product[1 + x^d[[i]], {i, Length[d]}], {x, 0, n}], n]; If[c <= 0, AppendTo[a, n]]]; a (* after T. D. Noe at A005835 and Michael De Vlieger at A188999 *)

CROSSREFS

Cf. A006037, A064114, A188999, A292982, A292985.

Sequence in context: A298463 A275295 A306984 * A064114 A319735 A258374

Adjacent sequences:  A292983 A292984 A292985 * A292987 A292988 A292989

KEYWORD

nonn

AUTHOR

Amiram Eldar, Sep 27 2017

STATUS

approved

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Last modified June 20 12:04 EDT 2021. Contains 345164 sequences. (Running on oeis4.)