A361925 Infinitary phi-practical (A361922) whose infinitary divisors have distinct values of the infinitary totient function iphi (A091732).
1, 3, 12, 15, 60, 105, 108, 132, 156, 165, 195, 240, 255, 660, 960, 1020, 1140, 1155, 1188, 1380, 1680, 1716, 1728, 1740, 1785, 1860, 1995, 2052, 2145, 2220, 2244, 2415, 2460, 2484, 2496, 2508, 2580, 2640, 2652, 2805, 2820, 2940, 3036, 3045, 3120, 3132, 3135, 3180
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
f[p_, e_] := p^(2^(-1 + Position[Reverse@ IntegerDigits[e, 2], 1])); iphi[1] = 1; iphi[n_] := Times @@ (Flatten@ (f @@@ FactorInteger[n]) - 1); idivs[n_] := Sort@ Flatten@ Outer[Times, Sequence @@ (FactorInteger[n] /. {p_, m_Integer} :> p^Select[Range[0, m], BitOr[m, #] == m &])]; idivs[1] = {1}; iPhiPracticalQ[n_] := Module[{s = Sort@Map[iphi, idivs[n]], ans = True}, Do[If[s[[j]] > Sum[s[[i]], {i, 1, j - 1}] + 1, ans = False; Break[]], {j, 1, Length[s]}]; ans]; Select[Range[3200], UnsameQ @@ iphi /@ idivs[#] && iPhiPracticalQ[#] &]
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