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A138578 Numbers n such that 2^(2*n-7)-7 is prime. 0
4, 23, 361, 995, 1163, 1253 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

2^(2*23-7)-7=549755813881,

2^(2*361-7)-7=172364133221937103085272756482216056112753534658909761028039668631756215232006\

744379020625060744018369805777923479247838020220755974022884986972234404720831\

691332769255536872593544438018353486799545737272878084128761

MATHEMATICA

q=7; For[i=q, i<=q, a={}; Do[x=2^(2*n-i)-i; If[PrimeQ[x], AppendTo[a, n]], {n, 10^2}]; Print["2^(2*n-", i, ")-", i, " ", a]; i=i+2]

PROG

(PARI) is(n)=isprime(2^(2*n-7)-7) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A327367 A303652 A130890 * A219932 A266919 A219464

Adjacent sequences:  A138575 A138576 A138577 * A138579 A138580 A138581

KEYWORD

nonn,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 13 2008

STATUS

approved

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Last modified December 9 09:21 EST 2019. Contains 329877 sequences. (Running on oeis4.)