

A294030


Values of bphi(n) = bphi(n+1), where bphi is the biunitary analog of Euler's totient function (A116550).


0



1, 9, 14, 42, 161, 161, 798, 1400, 86156, 123656, 419430
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OFFSET

1,2


COMMENTS

The biunitary totient function of numbers n such that n and n+1 have the same function value (A293184).
The biunitary 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 JeanFrançois 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



