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A144550
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Largest non-twin prime < n-th and (n+1)-th twin primes.
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1
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2, 23, 37, 53, 67, 97, 131, 173, 223, 233, 263, 277, 307, 337, 409, 457, 509, 563, 593, 613, 631, 653, 797, 853, 877, 1013, 1039, 1087, 1129, 1223, 1259, 1283, 1297, 1307, 1423, 1447, 1471, 1601, 1613, 1663, 1693, 1709, 1783, 1867, 1913, 1993, 2017, 2069
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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isA077800 := proc(n) isprime(n) and ( isprime(n+2) or isprime(n-2)) ; end proc:
isA007510 := proc(n) isprime(n) and not isA077800(n) ; end proc:
isA144550 := proc(n) isA007510(n) and isA077800( nextprime(n)) ; end proc:
for n from 2 to 2500 do if isA144550(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, May 01 2010
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MATHEMATICA
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Module[{nn=400, tps}, tps=Union[Flatten[Select[Partition[Prime[Range[nn]], 2, 1], #[[2]]-#[[1]] == 2&]]]; Complement[NextPrime[#, -1]&/@tps, tps]] (* Harvey P. Dale, Jun 23 2022 *)
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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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STATUS
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approved
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