1,3

Table of n, a(n) for n=1..73.

a(n) = A075255(A002808(n)) = A002808(n) - A001414(A002808(n)).

a(1) = 4 - (2+2) = 0; a(2) = 6 - (2+3) = 1; a(3) = 8 - (2+2+2) = 2 ; a(4) = 9 - (3+3) = 3; a(5) = 10 - (2+5) = 3.

(PARI) A145834(n)={for(k=0, primepi(n), isprime(n++)&k--); n+0-sum(i=1, #n=factor(n)~, n[1, i]*n[2, i])} [From M. F. Hasler, Oct 31 2008]

Cf. A001414, A002808, A075255.

Sequence in context: A159050 A210336 A280271 * A130006 A099609 A120249

Adjacent sequences: A145831 A145832 A145833 * A145835 A145836 A145837

nonn

Alexander R. Povolotsky, Oct 20 2008

Edited and extended by Ray Chandler, Oct 24 2008

approved