

A100006


Integer log of 2n: sum of primes dividing 2n (with repetition).


0



2, 4, 5, 6, 7, 7, 9, 8, 8, 9, 13, 9, 15, 11, 10, 10, 19, 10, 21, 11, 12, 15, 25, 11, 12, 17, 11, 13, 31, 12, 33, 12, 16, 21, 14, 12, 39, 23, 18, 13, 43, 14, 45, 17, 13, 27, 49, 13, 16, 14, 22, 19, 55, 13, 18, 15, 24, 33, 61, 14, 63, 35, 15, 14, 20, 18, 69, 23, 28, 16, 73, 14, 75
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OFFSET

1,1


LINKS

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


EXAMPLE

a(20)=11 because 40=2^3*5^1 and 3*2+1*5=11.


MAPLE

with(numtheory): a:=proc(n) local b: b:=op(2, ifactors(n)): add(b[j][1]*b[j][2], j=1..nops(b)): end: seq(a(2*n), n=1..88); # Emeric Deutsch, Mar 10 2005


MATHEMATICA

Table[Plus @@ Times @@@ FactorInteger[2n], {n, 100}] (* Ray Chandler, Nov 12 2005 *)


CROSSREFS

Bisection of A001414.
Sequence in context: A058317 A278761 A287076 * A196262 A238461 A195994
Adjacent sequences: A100003 A100004 A100005 * A100007 A100008 A100009


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane, Nov 20 2004


EXTENSIONS

More terms from Emeric Deutsch, Mar 10 2005


STATUS

approved



