OFFSET
1,2
COMMENTS
It seems that a(n+1)>2*a(n). - Benoit Cloitre, Aug 26 2002
a(n+1)=2*a(n)+1 if and only if n+1 is prime. - Benoit Cloitre, Dec 04 2002
LINKS
T. D. Noe, Table of n, a(n) for n=1..300
FORMULA
a(n) = M(n, 1) (see A074586 for definition of M(n, x)). a(n) mod 2 = A008966(n). a(n) is asymptotic to c*2^n with c=1.530191414016549187154362361492633020259512374111... Benoit Cloitre, Dec 04 2002
a(1)=1 a(n)=1+sum(i=1, n-1, floor(n/i)*a(i)). - Benoit Cloitre, Dec 04 2002
EXAMPLE
a(5) = M(5,1) = 1+9+15+10+2 = 37, since M(5,x) = 1 + 9x +15x^2 +10x^3 + 2x^4.
MATHEMATICA
m[n_, x_] := m[n, x]=1+x*Sum[m[i, x]Floor[n/i], {i, 1, n-1}]; Table[m[n, 1], {n, 1, 40}]
CROSSREFS
KEYWORD
easy,nice,nonn
AUTHOR
Paul D. Hanna, Aug 25 2002
EXTENSIONS
Cross reference corrected by Mats Granvik, Apr 23 2010
STATUS
approved