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A121765 Numbers n such that 6n-1 is composite while 6n+1 is prime. 5
6, 11, 13, 16, 21, 26, 27, 35, 37, 46, 51, 55, 56, 61, 62, 63, 66, 68, 73, 76, 81, 83, 90, 91, 96, 101, 102, 105, 112, 115, 118, 121, 122, 123, 125, 126, 128, 131, 142, 146, 151, 153, 156, 161, 165, 166, 168, 173, 178, 181, 186, 187, 188, 195, 200, 202, 206, 208, 216 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Entries in A046953 which are not in A060461 or equivalently,entries in A024899 which are not in A002822.

MATHEMATICA

Select[Range[250], ! PrimeQ[6# - 1] && PrimeQ[6# + 1] &] (*Chandler*)

CROSSREFS

Cf. A121764.

Sequence in context: A004471 A175021 A046953 * A102974 A154293 A199717

Adjacent sequences:  A121762 A121763 A121764 * A121766 A121767 A121768

KEYWORD

nonn

AUTHOR

Lekraj Beedassy (blekraj(AT)yahoo.com), Aug 20 2006

EXTENSIONS

Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 22 2006

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Last modified February 17 06:13 EST 2012. Contains 205991 sequences.