A372469 a(n) = log_2(A372468(n)).

0, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 2, 1, 2, 2, 3, 1, 3, 1, 2, 1, 2, 1, 3, 2, 3, 2, 2, 1, 1, 2, 2, 3, 1, 2, 3, 1, 1, 2, 2, 3, 1, 2, 1, 2, 2, 2, 3, 1, 2, 2, 2, 2, 1, 1, 3, 1, 3, 3, 2, 1, 1, 3, 2, 1, 3, 2, 2, 2, 4, 2, 2, 2

Offset: 1

Author

Amiram Eldar, May 02 2024

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A372468.

Programs

Mathematica

f[n_] := Module[{p = Times @@ (1 + FactorInteger[n][[;; , 2]]), e}, e = IntegerExponent[p, 2]; If[p == 2^e, e, Nothing]]; f[1] = 0; Array[f, 150]

PARI

lista(kmax) = {my(p, e); for(k = 1, kmax, p = vecprod(apply(x -> x + 1, factor(k)[, 2])); e = valuation(p, 2); if(p >> e == 1, print1(e, ", "))); }