Search: id:A124247
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%I A124247
%S A124247 41,91,299,341
%N A124247 Numbers n such that n!!-8 and n!!+8 are two consecutive primes.
%C A124247 n is in the sequence iff n!!-8 and n!!+8 are primes and the four numbers 
               n!!-2,n!!+2, n!!-4 & n!!+4 are composites. It's interesting that 
               related to the term 341 we can say 341!!-(3+4+1) and 341!!+(3+4+1) 
               are two consecutive primes with length 341+prime(3+4+1). Conjecture: 
               341 is the largest term of this sequence.
%e A124247 341 is in the sequence because 341!!-8 and 341!!+8 are primes and the 
               four numbers 341!!-2, 341!!+2, 341!!-4 & 341!!+4 are composites.
%t A124247 Select[Range[5,500],PrimeQ[ #!!-8]&&PrimeQ[ #!!+8]&&!PrimeQ[ #!!-4] &&!PrimeQ[ 
               #!!+4]&&!PrimeQ[ #!!-2]&&!PrimeQ[ #!!+2]&]
%Y A124247 Cf. A076188.
%Y A124247 Sequence in context: A044179 A044560 A039469 this_sequence A142658 A126588 
               A142794
%Y A124247 Adjacent sequences: A124244 A124245 A124246 this_sequence A124248 A124249 
               A124250
%K A124247 nonn
%O A124247 1,1
%A A124247 Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 19 2006

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