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A074054 Numbers n such that sum of composites from smallest prime factor of n to largest prime factor of n is prime. 1

%I #10 Dec 15 2017 17:36:00

%S 22,33,44,66,88,99,106,110,132,134,154,155,159,165,176,178,198,201,

%T 202,206,212,220,231,242,264,267,268,297,303,308,309,318,330,334,352,

%U 356,363,371,396,402,404,412,413,424,440,445,462,469,477,484,493,495,501

%N Numbers n such that sum of composites from smallest prime factor of n to largest prime factor of n is prime.

%H Harvey P. Dale, <a href="/A074054/b074054.txt">Table of n, a(n) for n = 1..1000</a>

%e 22=2*11 and sum of composites between 2 and 11 is: 4+6+8+9+10 = 37, prime.

%t scpQ[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]],a,b},a = First[f]+ 1;b=Last[f]-1;PrimeQ[Total[Select[Range[a,b],!PrimeQ[#]&]]]]; Select[ Range[ 510],scpQ] (* _Harvey P. Dale_, May 07 2013 *)

%K nonn

%O 1,1

%A _Jason Earls_, Sep 15 2002

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Last modified July 27 07:48 EDT 2024. Contains 374642 sequences. (Running on oeis4.)