

A108184


a(n) = smallest prime such that a(n) + 2n is also prime and such that a(n) > a(n1).


3



2, 3, 7, 11, 23, 31, 41, 47, 67, 71, 83, 109, 113, 131, 139, 149, 167, 193, 197, 233, 241, 251, 263, 271, 283, 317, 331, 347, 353, 373, 379, 401, 439, 443, 479, 487, 491, 503, 523, 541, 563, 571, 577, 587, 613, 619, 641, 727, 733, 761, 787, 809, 863, 877
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OFFSET

0,1


COMMENTS

Increasing primes p such that p + 2n is prime.


LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000


EXAMPLE

a(0)=2 since 2+0=2 is prime; a(1)=3 since 3+2=5 is prime.
a(2)=7 since 7+4=11 is prime; 5 is not in the sequence since 5+4=9 is not prime.


MAPLE

A108184 := proc(n) option remember; if n = 1 then 3; else for a from procname(n1)+1 do if isprime(a) and isprime(a+2*n) then RETURN(a) ; fi; od: fi; end: seq(A108184(n), n=1..100) ; # R. J. Mathar, Jan 31 2009


MATHEMATICA

t = {2}; Do[p = NextPrime[t[[1]]]; While[! PrimeQ[p + 2 n], p = NextPrime[p]]; AppendTo[t, p], {n, 100}]; t (* T. D. Noe, Feb 04 2014 *)


PROG

(PARI) A108184(maxp) = {my(a=[2], n=1); forprime(p=3, maxp, if(isprime(p+2*n), n++; a=concat(a, p))); a} \\ Colin Barker, Feb 03 2014


CROSSREFS

Cf. A020483, A237055
Sequence in context: A228592 A034795 A165318 * A049091 A039787 A267503
Adjacent sequences: A108181 A108182 A108183 * A108185 A108186 A108187


KEYWORD

easy,nonn


AUTHOR

Giovanni Teofilatto, Jun 28 2005


EXTENSIONS

Edited and extended by Ray Chandler, Jul 07 2005
Edited by N. J. A. Sloane, Feb 11 2009 at the suggestion of R. J. Mathar


STATUS

approved



