A102441 a(n) = A102440(A102440(n)).

1, 2, 3, 4, 4, 6, 6, 8, 9, 8, 8, 12, 8, 12, 12, 16, 12, 18, 12, 16, 18, 16, 20, 24, 16, 16, 27, 24, 20, 24, 20, 32, 24, 24, 24, 36, 24, 24, 24, 32, 30, 36, 30, 32, 36, 40, 44, 48, 36, 32, 36, 32, 45, 54, 32, 48, 36, 40, 52, 48, 52, 40, 54, 64, 32, 48, 40, 48, 60, 48, 66, 72, 66

Offset: 1

Author

Reinhard Zumkeller, Jan 09 2005

Keywords

• nonn
• mult

Comments

See A102442, A102443 for further iterations of A102440.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A102440, A102442, A102443.

Programs

Mathematica

g[p_] := g[p] = For[k = p - 1, True, k--, If[PrimeOmega[k] == 2, Return[k]]]; f[n_] := Product[{p, e} = pe; If[p <= 3, p, g[p]]^e, {pe, FactorInteger[n]}]; a[n_] := f[f[n]]; Array[a, 100] (* Amiram Eldar, Feb 04 2020 after Jean-François Alcover at A102440 *)