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A152908
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Primes p=prime(k) such that p - nonprime(k) is prime and p + nonprime(k) is not prime, where prime(n) is the n-th prime and nonprime(n) is the n-th nonprime starting with nonprime(1) = 0.
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1
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3, 17, 37, 53, 71, 79, 113, 127, 151, 167, 277, 317, 383, 397, 419, 421, 509, 577, 599, 641, 643, 653, 683, 761, 797, 829, 877, 937, 1049, 1051, 1087, 1097, 1163, 1249, 1283, 1297, 1367, 1439, 1483, 1607, 1699, 1913, 1933, 1993, 2017, 2081, 2089, 2129, 2131
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OFFSET
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1,1
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LINKS
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EXAMPLE
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3(2) - 1(2) = 2 (prime) and 3(2) + 1(2) = 4 (nonprime), so 3 is in the sequence.
17(7) - 10(7) = 7 (prime) and 17(7) + 10(7) = 27 (nonprime), so 17 is in the sequence.
37(12) - 18(12) = 19 (prime) and 37(12) + 18(12) = 55 (nonprime), so 37 is in the sequence.
53(16) - 24(16) = 29(prime) and 53(16) + 24(16) = 77 (nonprime), so 53 is in the sequence.
71(20) - 28(20) = 43(prime) and 71(20) + 28(20) = 99 (nonprime), so 71 is in the sequence.
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MAPLE
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A141468 := proc(n) option remember ; local a; if n = 1 then 0 ; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od; fi; end: for n from 1 to 700 do p := ithprime(n) ; if isprime( p- A141468(n)) and not isprime(p+A141468(n)) then printf("%d, ", p) ; fi; od: # R. J. Mathar, Jan 17 2009
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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227, 619, 1039, etc. removed, and 797, 1087, etc. added, by R. J. Mathar, Jan 17 2009
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STATUS
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approved
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