OFFSET
1,6
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
EXAMPLE
p(1,n) = 1, so a(1)=0
p(2,n) = x, so a(2)=1
p(6,n) = x(1+x), so a(6)=2
p(18,n) = x(x+1)(1-x+x^2), so a(18)=3
p(90,n) = x(1+x)(1+x^2)(1-x+x^2), so a(90)=4
MATHEMATICA
t = Table[IntegerDigits[n, 2], {n, 1, 1000}];
b[n_] := Reverse[Table[x^k, {k, 0, n}]]
p[n_, x_] := p[n, x] = t[[n]].b[-1 + Length[t[[n]]]]
TableForm[Table[{n, p[n, x],
FactorList[p[n, x]], -1 + Length[FactorList[p[n, x]]]}, {n, 1, 9}]]
Table[Length[FactorList[p[n, x]]], {n, 1, 120}]
PROG
(PARI) A206719(n) = { my(f = factor(Pol(binary(n)))); (#f~); }; \\ Antti Karttunen, Dec 16 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Feb 11 2012
STATUS
approved