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A166685 Odd numbers that are the sum of two consecutive nonprimes. 3

%I #12 Mar 07 2020 22:14:43

%S 1,5,17,19,29,31,41,43,49,51,53,55,65,67,69,71,77,79,89,91,97,99,101,

%T 103,109,111,113,115,125,127,129,131,137,139,149,151,153,155,161,163,

%U 169,171,173,175,181,183,185,187,189,191,197,199,209,211,221,223,229

%N Odd numbers that are the sum of two consecutive nonprimes.

%H Harvey P. Dale, <a href="/A166685/b166685.txt">Table of n, a(n) for n = 1..1000</a>

%e a(1)=0(1st nonprime)+1(2nd nonprime)=1(odd);

%e a(2)=1(2nd nonprime)+4(3rd nonprime)=5(odd).

%t Select[Total/@Partition[Select[Range[0,200],!PrimeQ[#]&],2,1],OddQ] (* _Harvey P. Dale_, Mar 07 2020 *)

%Y Cf. A118134, A141468, A163467.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Oct 18 2009

%E Entries checked by _R. J. Mathar_, Apr 24 2010

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Last modified July 20 15:17 EDT 2024. Contains 374459 sequences. (Running on oeis4.)