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A210934 Sum of prime factors of prime(n)+1 (counted with multiplicity). 5
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, 19, 13, 18, 24, 14, 18, 28, 16, 15, 25, 81, 45, 16, 34, 15, 22, 15, 99, 19, 16, 57, 17, 26, 30, 21, 16, 24, 17, 48, 20, 16, 25, 141, 52, 75, 19, 22, 22, 159, 58, 87 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
From an idea of Michael B. Porter.
LINKS
FORMULA
a(n) = A001414(A008864(n)). - Michel Marcus, Oct 05 2013
EXAMPLE
prime(8) = 19, and 19+1 = 20 = 2*2*5, so a(8) = 2+2+5 = 9.
MAPLE
with(numtheory);
P:=proc(i)
local a, k, n;
for n from 1 to i do
a:=ifactors(ithprime(n)+1)[2]; print(add(a[k][1]*a[k][2], k=1..nops(a)));
od; end:
# alternative
A210934 := proc(n)
local p, pplus, f ;
p := ithprime(n) ;
pplus := ifactors(p+1)[2] ;
add(op(1, f)*op(2, f), f=pplus) ;
end proc:
seq(A210934(n), n=1..300) ; # R. J. Mathar, May 25 2022
CROSSREFS
Sequence in context: A037350 A014615 A144046 * A354774 A194276 A184336
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Mar 30 2012
STATUS
approved

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)