

A144586


a(n) = odd and nonprime sum of prime factors of composite(k) = A002808(k).


0



9, 9, 9, 15, 9, 21, 15, 25, 33, 21, 39, 45, 27, 49, 15, 55, 15, 33, 63, 35, 15, 15, 69, 75, 15, 25, 81, 15, 45, 85, 25, 91, 15, 51, 15, 99, 21, 105, 21, 57, 15, 111, 115, 21, 35, 21, 63, 15, 65, 129, 25, 35, 133, 25, 21, 141, 75, 27, 77, 153, 27, 25, 159, 165, 21, 87, 169, 27
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OFFSET

1,1


LINKS



EXAMPLE

At k=7, A002808(k) = 14 = 2*7, and 2 + 7 = 9 (an odd nonprime), and k=7 is the smallest index for which this occurs, so a(1)=9.
At k=11, A002808(k) = 20 = 2*2*5, and 2 + 2 + 5 = 9 (an odd nonprime), and k=11 is the 2nd smallest index for which this occurs, so a(2)=9.
At k=14, A002808(k) = 24 = 2*2*2*3, and 2 + 2 + 2 + 3 = 9 (an odd nonprime), and k=24 is the 3rd smallest index for which this occurs, so a(3)=9.
At k=16, A002808(k) = 26 = 2*13 and 2 + 13 = 15 (an odd nonprime), and k=26 is the 4th smallest index for which this occurs, so a(4)=15, etc.


MAPLE

pss := proc(n) a := 0 ; for d in ifactors(n)[2] do a := a+ op(2, d)*op(1, d) ; end do: a ; end proc:
A002808 := proc(n) if n = 1 then 4; else for a from procname(n1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc:
for k from 1 to 800 do a := A046343(k) ; if not isprime(a) and type(a, 'odd') then printf("%d, ", a) ; end if; end do: # (End)


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS

Corrected at two or more places and extended by R. J. Mathar, May 01 2010


STATUS

approved



