login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A284521 Sum of largest prime power factors of numbers <= n. 1

%I

%S 1,3,6,10,15,18,25,33,42,47,58,62,75,82,87,103,120,129,148,153,160,

%T 171,194,202,227,240,267,274,303,308,339,371,382,399,406,415,452,471,

%U 484,492,533,540,583,594,603,626,673,689,738,763,780,793,846,873,884,892,911,940,999,1004,1065,1096,1105,1169,1182

%N Sum of largest prime power factors of numbers <= n.

%C Partial sums of A034699.

%H Robert Israel, <a href="/A284521/b284521.txt">Table of n, a(n) for n = 1..10000</a>

%F Conjecture: a(n) = O(n^2/log(n)).

%e a(1) = 1;

%e a(2) = 3 because 2 is a prime and 1 + 2 = 3;

%e a(3) = 6 because 3 is a prime and 3 + 3 = 6;

%e a(4) = 10 because 4 = 2^2 and 6 + 4 = 10;

%e a(5) = 15 because 5 is a prime and 10 + 5 = 15;

%e a(6) = 18 because 12 = 2*3 and 15 + 3 = 18, etc.

%p g:= n -> max(map(t -> t[1]^t[2], ifactors(n)[2])): g(1):= 1:

%p ListTools:-PartialSums(map(g, [$1..100])); # _Robert Israel_, Mar 29 2017

%t Accumulate[Join[{1}, Table[Last[Select[Divisors[n], PrimePowerQ[#1] & ]], {n, 2, 65}]]]

%o (PARI) a(n) = if (n==1, 1, 1+ sum(k=2, n, f = factor(k); f[#f~,1]^f[#f~,2])); \\ _Michel Marcus_, Mar 28 2017

%Y Cf. A034699, A046670, A073355.

%K nonn

%O 1,2

%A _Ilya Gutkovskiy_, Mar 28 2017

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 23 09:23 EST 2018. Contains 299503 sequences. (Running on oeis4.)