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Search: id:A075322
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| A075322 |
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Pair the odd primes so that the k-th pair is (p, p+2k) where p is the smallest prime not included earlier such that p and p+2k are primes and p+2k also does not occur earlier: (3, 5), (7, 11), (13, 19), (23, 31), (37, 47), (17, 29), ... This is the sequence of the second member of every pair. |
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+0
3
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| 5, 11, 19, 31, 47, 29, 59, 71, 61, 73, 89, 103, 109, 127, 131, 139, 149, 173, 151, 197, 211, 223, 227, 239, 251, 281, 311, 97, 293, 307, 331, 263, 233, 313, 347, 359, 317, 241, 271, 419, 367, 421, 439, 461, 479, 443, 491, 379, 499, 449, 487, 521, 541, 523
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Question: Is every prime p a member of some pair?
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PROGRAM
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(PARI) v=vector(10^5):for(n=1, 100, f=0:i=3:while(!f, while(v[i], i=nextprime(i+1)):if(isprime(i+2*n)&&!v[i+2*n], f=1:v[i]=1:v[i+2*n]=1:print1(i+2*n", "):break, i=i+1)))
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CROSSREFS
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Equals A075321(n)+2n, also A075323(2n).
Sequence in context: A100920 A003147 A106068 this_sequence A079850 A065995 A023245
Adjacent sequences: A075319 A075320 A075321 this_sequence A075323 A075324 A075325
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 14 2002
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EXTENSIONS
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More terms from Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 27 2003
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