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A067189 Numbers that can be expressed as the sum of two primes in exactly three ways. 12

%I #16 Mar 10 2022 10:34:43

%S 22,24,26,30,40,44,52,56,62,98,128

%N Numbers that can be expressed as the sum of two primes in exactly three ways.

%C Corresponds to numbers 2m such that A045917(m)=3. Subsequence of A014091. - _Lekraj Beedassy_, Apr 22 2004

%H <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a>

%e 26 is a term as 26 = 23+3 = 19+7 = 13+13 are all the three ways to express 26 as a sum of two primes.

%Y Cf. A023036.

%Y Numbers that can be expressed as the sum of two primes in k ways for k=0..10: A014092 (k=0), A067187 (k=1), A067188 (k=2), this sequence (k=3), A067190 (k=4), A067191 (k=5), A066722 (k=6), A352229 (k=7), A352230 (k=8), A352231 (k=9), A352233 (k=10).

%K nonn,fini,full

%O 1,1

%A _Amarnath Murthy_, Jan 10 2002

%E Extended by Peter Bertok (peter(AT)bertok.com), who finds (Jan 13 2002) that there are no other terms below 10000 and conjectures there are no further terms in this sequence and A067188, A067190, etc.

%E _R. K. Guy_ (Jan 14 2002) remarks: "I believe that these conjectures follow from a more general one by Hardy & Littlewood (probably in Some problems of 'partitio numerorum' III, on the expression of a number as a sum of primes, Acta Math. 44(1922) 1-70)."

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)