A290304 Values of uphi(k) = uphi(k+1).

1, 12, 24, 120, 96, 180, 432, 744, 720, 864, 840, 1200, 1260, 1680, 2520, 1728, 2784, 2880, 3744, 4032, 5040, 2592, 4224, 5040, 5760, 11520, 11880, 9216, 18000, 20160, 17280, 12480, 17280, 20160, 28080, 20160, 23040, 21600, 32256, 30240, 52080, 34560, 57600

Offset: 1

Author

Amiram Eldar, Jul 26 2017

Keywords

• nonn

Comments

The values of unitary totient function of numbers such that k and k+1 have the same value.

The unitary version of A003275.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..2198

Crossrefs

Cf. A001274, A003275, A047994, A287055.

Programs

Mathematica

uphi[n_] := If[n==1, 1, (Times @@ (Table[#[[1]]^#[[2]] - 1, {1}] & /@ FactorInteger[n]))[[1]]]; a={}; u1=0; For[k=0, k<10^5, k++; u2=uphi[k]; If[u1==u2, a = AppendTo[a, u1]]; u1=u2]; a

Formula

a(n) = A047994(A287055(n)).