A384812 - OEIS

%I #11 Jul 25 2025 02:18:26

%S 0,2,2,3,2,4,2,5,3,4,2,5,2,4,4,7,2,5,2,5,4,4,2,7,3,4,5,5,2,6,2,11,4,4,

%T 4,6,2,4,4,7,2,6,2,5,5,4,2,9,3,5,4,5,2,7,4,7,4,4,2,7,2,4,5,13,4,6,2,5,

%U 4,6,2,8,2,4,5,5,4,6,2,9,7,4,2,7,4,4,4,7,2,7

%N If n = Product prime(i)^e(i) then a(n) = Sum prime(e(i)).

%H Robert Israel, <a href="/A384812/b384812.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>.

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>.

%p f:= proc(n) local t;

%p   add(ithprime(t[2]),t=ifactors(n)[2])

%p end proc:

%p map(f, [$1..100]); # _Robert Israel_, Jul 25 2025

%t Table[Plus @@ (Prime[#[[2]]] & /@ FactorInteger[n]), {n, 1, 90}]

%o (PARI) a(n) = my(f=factor(n)); sum(k=1, #f~, prime(f[k,2])); \\ _Michel Marcus_, Jun 10 2025

%Y Cf. A001222, A001414, A008472, A066328, A181819, A366988.

%K nonn

%O 1,2

%A _Ilya Gutkovskiy_, Jun 10 2025