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A100006 Integer log of 2n: sum of primes dividing 2n (with repetition). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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: A278761 A287076 A344587 * A196262 A238461 A195994
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 20 2004
EXTENSIONS
More terms from Emeric Deutsch, Mar 10 2005
STATUS
approved

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Last modified March 2 20:50 EST 2024. Contains 370498 sequences. (Running on oeis4.)