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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

Table of n, a(n) for n=1..11.

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-Fran├žois 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.)