Sequences Involving Binary & Prime-Factorization
Leroy Quet
qq-quet at mindspring.com
Thu Feb 19 23:00:30 CET 2004
[posted also to sci.math]
First, we have the sequence formed by simply letting
a(m) = 1, if the sum of all exponents of the prime-factorization of m has
no carries when summed in in base-2.
a(m) = 0, if there are any carries in the summing of the exponents of the
prime-factorization of m.
So, for example,
a(12) = 1 because 12 = 2^2 *3^1,
and, in base-2, 2 = '10', 1 = '1',
and '10' and '1' have their ones in different positions.
But,
a(24) = 0, because 24 = 2^3 *3^1,
and, in base-2, 3 = '11', 1 = '1',
which both share a rightmost one.
Unless I made an error, this sequence is not yet in the Encyclopedia Of
Integer Sequences.
a(k) -> 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1,...
(Defining a(1) = 1 makes b()-recursion below work.)
Now, let b(m) =
sum{k=1 to m} a(k).
b(m) gives the number of positive integers <= m and with an a() of 1,
obviously.
My main math result related to these sequences:
(a somewhat interesting method of calculating {b()} using recursion):
b(1) = 1;
b(m) =
b(floor(sqrt(m)) + sum{p=primes<=m} b(floor(sqrt(m/p))),
(or, if we choose to define 1 as a prime:
b(m) =
sum{p=primes<=m} b(floor(sqrt(m/p))) )
And, unless I made an error, this sequence is not yet in the Encyclopedia
Of Integer Sequences either.
b(k) -> 1, 2, 3, 4, 5, 5, 6, 7, 8, 8, 9, 10, 11, 11, 11, 12, 13,...
thanks,
Leroy Quet
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