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Search: id:A060255
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| A060255 |
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Smaller of twin primes {p,p+2} such that the middle term p+1 = kq is the least multiple of the n-th primorial number q. |
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2
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| 3, 5, 29, 419, 2309, 180179, 4084079, 106696589, 892371479, 103515091679, 4412330782859, 29682952539239, 22514519501013539, 313986271960080719, 22750921955774182169, 912496437361321252439, 26918644902158976946979
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n)=p=k(n)*q(n)-1, where q(n)=A002110(n) and k(n)=A060256(n) is the smallest integer if by which the n-th primorial was multiplied then just these lesser twin primes were obtained.
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EXAMPLE
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a(13)=-1+(2.3.5.7.....41)*k(13)=304250263527210*74 and {22514519501013539, 22514519501013542} are the corresponding primes, k(13)=74 is the smallest suitable multiplier. Twin primes obtained from primorial numbers with k=1 multiplier seems to be much rarer (see A057706).
For j=1,2,3,4,5,6, a(j)=A001359(1), A059960(1), A060229(1), A060230(1), A060231(1), A060232(1) respectively.
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CROSSREFS
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Cf. A001359, A002110, A006794, A014545, A057706, A059960, A060229-A060232.
Sequence in context: A154942 A092330 A082716 this_sequence A154552 A100857 A100856
Adjacent sequences: A060252 A060253 A060254 this_sequence A060256 A060257 A060258
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Mar 22 2001
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EXTENSIONS
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a(2)=5 corrected by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 03 2009
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