1,2

Integer log of (2n-1): sum of primes dividing 2n-1 (with repetition). - Emeric Deutsch, Mar 10 2005

Table of n, a(n) for n=1..69.

a(23)=11 because 45=3^2*5^1 and 2*3+1*5=11.

with(numtheory): a:=proc(n) local b: b:=op(2, ifactors(n)): sum(b[j][1]*b[j][2], j=1..nops(b)): end: seq(a(2*n-1), n=1..78); (Deutsch)

Sequence in context: A219781 A215107 A084393 * A215457 A130159 A127314

Adjacent sequences: A100002 A100003 A100004 * A100006 A100007 A100008

nonn,easy

N. J. A. Sloane, Nov 20 2004

More terms from Emeric Deutsch, Mar 10 2005

approved