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A089192 Numbers n such that 2n - 7 is a prime. 25
5, 6, 7, 9, 10, 12, 13, 15, 18, 19, 22, 24, 25, 27, 30, 33, 34, 37, 39, 40, 43, 45, 48, 52, 54, 55, 57, 58, 60, 67, 69, 72, 73, 78, 79, 82, 85, 87, 90, 93, 94, 99, 100, 102, 103, 109, 115, 117, 118, 120, 123, 124, 129, 132, 135, 138, 139, 142, 144, 145, 150, 157, 159, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Solutions of the equation (2*n-7)' = 1, where n' is the arithmetic derivative of n. - Paolo P. Lava, Nov 15 2012

REFERENCES

M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997

LINKS

Shawn A. Broyles, Table of n, a(n) for n = 1..1000

MATHEMATICA

lst={}; Do[If[PrimeQ[2*n-7], (*Print[n]; *)AppendTo[lst, n]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 26 2008 *)

Select[Range[3, 200], PrimeQ[2#-7]&] (* Harvey P. Dale, Aug 24 2014 *)

PROG

(PARI) is(n)=isprime(2*n - 7) \\ Charles R Greathouse IV, Apr 28 2015

CROSSREFS

Numbers n such that 2n+k is prime: A005097 (k=1), A067076 (k=3), A089038 (k=5), A105760 (k=7), A155722 (k=9), A101448 (k=11), A153081 (k=13), A089559 (k=15), A173059 (k=17), A153143 (k=19).

Numbers n such that 2n-k is prime: A006254 (k=1), A098090 (k=3), A089253 (k=5), this sequence (k=7), A097069 (k=9), A097338 (k=11), A097363 (k=13), A097480 (k=15), A098605 (k=17), A097932 (k=19).

Sequence in context: A066263 A178096 A246782 * A279195 A232710 A132829

Adjacent sequences:  A089189 A089190 A089191 * A089193 A089194 A089195

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Dec 08 2003

EXTENSIONS

Corrected by Ralf Stephan, Mar 03 2004

Further correction from Jeremy Gardiner, Sep 11 2004

STATUS

approved

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Last modified August 20 03:33 EDT 2019. Contains 326139 sequences. (Running on oeis4.)