1,4

Table of n, a(n) for n=1..74.

a(n) = card( k : sigma(k) < n ); a(n) is asymptotic to c*n with c=0.67...

(PARI) a(n)=sum(i=1, n, if(1+sign(sigma(i)-n), 0, 1))

Sequence in context: A157222 A064047 A111899 * A013928 A172104 A006161

Adjacent sequences: A074750 A074751 A074752 * A074754 A074755 A074756

nonn

Benoit Cloitre, Sep 28 2002

approved