login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A137288 Numbers k such that 2*prime(k)-1 is prime. 4
1, 2, 4, 8, 11, 12, 22, 25, 34, 37, 46, 47, 50, 58, 63, 67, 68, 73, 75, 85, 95, 101, 106, 110, 111, 114, 121, 125, 129, 141, 145, 151, 159, 163, 168, 169, 180, 193, 203, 207, 211, 222, 226, 232, 242, 254, 258, 260, 274, 285 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Carl R. White, Table of n, a(n) for n = 1..10000

EXAMPLE

k=11: 2*prime(11) - 1 = 2*31 - 1 = 61 is prime, so k=11 belongs to the sequence.

MAPLE

P:=proc(n) local a, i; for i from 1 by 1 to n do a:=2*ithprime(i)-1; if isprime(a) then print(i); fi; od; end: P(301); # Paolo P. Lava, Apr 15 2008

CROSSREFS

Cf. A000040, A005382 (corresponding primes).

Sequence in context: A274924 A080152 A136994 * A247524 A116443 A243181

Adjacent sequences:  A137285 A137286 A137287 * A137289 A137290 A137291

KEYWORD

easy,nonn

AUTHOR

Ctibor O. Zizka, Apr 05 2008

EXTENSIONS

More terms from Paolo P. Lava, Apr 15 2008

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 24 06:56 EDT 2019. Contains 321444 sequences. (Running on oeis4.)