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A210934 Sum of prime factors of prime(n)+1 (counted with multiplicity). 5

%I #30 May 25 2022 08:53:04

%S 3,4,5,6,7,9,8,9,9,10,10,21,12,15,11,11,12,33,21,12,39,13,14,13,16,22,

%T 19,13,18,24,14,18,28,16,15,25,81,45,16,34,15,22,15,99,19,16,57,17,26,

%U 30,21,16,24,17,48,20,16,25,141,52,75,19,22,22,159,58,87

%N Sum of prime factors of prime(n)+1 (counted with multiplicity).

%C From an idea of _Michael B. Porter_.

%H Paolo P. Lava, <a href="/A210934/b210934.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A001414(A008864(n)). - _Michel Marcus_, Oct 05 2013

%e prime(8) = 19, and 19+1 = 20 = 2*2*5, so a(8) = 2+2+5 = 9.

%p with(numtheory);

%p P:=proc(i)

%p local a,k,n;

%p for n from 1 to i do

%p a:=ifactors(ithprime(n)+1)[2]; print(add(a[k][1]*a[k][2],k=1..nops(a)));

%p od; end:

%p # alternative

%p A210934 := proc(n)

%p local p,pplus,f ;

%p p := ithprime(n) ;

%p pplus := ifactors(p+1)[2] ;

%p add(op(1,f)*op(2,f),f=pplus) ;

%p end proc:

%p seq(A210934(n),n=1..300) ; # _R. J. Mathar_, May 25 2022

%Y Cf. A023508, A023514, A210936

%K nonn

%O 1,1

%A _Paolo P. Lava_, Mar 30 2012

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Last modified April 24 10:11 EDT 2024. Contains 371935 sequences. (Running on oeis4.)