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 A136019 Smallest prime of the form (prime(k)+2*n)/(2*n+1), any k. 56
 3, 3, 5, 3, 3, 5, 3, 7, 11, 3, 3, 5, 5, 3, 11, 3, 3, 5, 3, 3, 5, 5, 7, 5, 3, 3, 7, 5, 13, 7, 3, 3, 5, 3, 13, 5, 3, 7, 5, 3, 3, 13, 5, 3, 7, 5, 3, 5, 3, 7, 7, 3, 7, 11, 3, 3, 5, 11, 3, 7, 7, 3, 5, 11, 3, 13, 3, 7, 5, 3, 7, 11, 7, 13, 7, 3, 3, 11, 23, 7, 5, 3, 31, 5, 13, 3, 5, 5, 3, 7, 3, 13, 7, 3, 3, 5, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The associated prime(k) are in A136020. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE a(1)=3 because 3 is smallest prime of the form (p+2)/3; in this case prime(k)=7. a(2)=3 because 3 is smallest prime of the form (p+4)/5; in this case prime(k)=11. a(3)=5 because 5 is smallest prime of the form (p+6)/7; in this case prime(k)=29. MAPLE N:= 10^5: # to allow prime(k) <= N Primes:= select(isprime, [2, seq(2*i+1, i=1..floor((N-1)/2))]): f:= proc(t, n)   local s;   s:= (t+2*n)/(1+2*n);   type(s, integer) and isprime(s) end proc: for n from 1 do   p:= ListTools:-SelectFirst(f, Primes, n);   if p = NULL then break fi;   A[n]:= (p+2*n)/(1+2*n); od: seq(A[i], i=1..n-1); # Robert Israel, Sep 08 2014 MATHEMATICA a = {}; Do[k = 1; While[ !PrimeQ[(Prime[k] + 2n)/(2n + 1)], k++ ]; AppendTo[a, (Prime[k] + 2n)/(2n + 1)], {n, 1, 200}]; a PROG (PARI) a(n)=my(N=2*n, k=0, t); forprime(p=2, default(primelimit), k++; t=(p+N)/(N+1); if(denominator(t)==1&isprime(t), return(t))) \\ Charles R Greathouse IV, Jun 16 2011 CROSSREFS Cf. A136020, A136026, A136027. Sequence in context: A269733 A138479 A202106 * A242017 A063714 A235649 Adjacent sequences:  A136016 A136017 A136018 * A136020 A136021 A136022 KEYWORD nonn,easy AUTHOR Artur Jasinski, Dec 10 2007 EXTENSIONS Edited by R. J. Mathar, May 17 2009 STATUS approved

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Last modified April 14 01:17 EDT 2021. Contains 342941 sequences. (Running on oeis4.)