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 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..68. 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 # R. J. Mathar, May 01 2010: (Start) 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(n-1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc: A046343 := proc(n) pss(A002808(n)) ; 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 Cf. A002808, A141468. Sequence in context: A344337 A293832 A277223 * A141557 A072563 A206011 Adjacent sequences: A144583 A144584 A144585 * A144587 A144588 A144589 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Jan 04 2009 EXTENSIONS Corrected at two or more places and extended by R. J. Mathar, May 01 2010 Example section edited by Jon E. Schoenfield, Oct 18 2015 STATUS approved

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Last modified August 10 05:56 EDT 2024. Contains 375044 sequences. (Running on oeis4.)