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 A294030 Values of bphi(n) = bphi(n+1), where bphi is the bi-unitary analog of Euler's totient function (A116550). 0
 1, 9, 14, 42, 161, 161, 798, 1400, 86156, 123656, 419430 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The bi-unitary totient function of numbers n such that n and n+1 have the same function value (A293184). The bi-unitary version of A003275. LINKS FORMULA a(n) = A116550(A293184(n)). EXAMPLE 9 is in the sequence since 9 = bphi(14) = bphi(15). MATHEMATICA bphi[1] = 1; bphi[n_] := With[{pp = Power @@@ FactorInteger[n]}, Count[Range[n], m_ /; Intersection[pp, Power @@@ FactorInteger[m]] == {}]]; a={}; b1=0; Do[b2 = bphi[k]; If[b1 == b2, a = AppendTo[a, b1]]; b1 = b2, {k, 1, 10^2}]; a (* after Jean-François Alcover at A116550 *) CROSSREFS Cf. A116550, A293184. Sequence in context: A066793 A275508 A139055 * A079625 A027009 A239038 Adjacent sequences:  A294027 A294028 A294029 * A294031 A294032 A294033 KEYWORD nonn,more AUTHOR Amiram Eldar, Oct 22 2017 EXTENSIONS a(10)-a(11) from Michel Marcus, Nov 14 2017 STATUS approved

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Last modified November 26 12:37 EST 2020. Contains 338639 sequences. (Running on oeis4.)