The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A283145 a(1)=5; for n > 1, and a(n) is the least prime p > a(n-1) such that both q = p + 2n and r = q + 2n + 2 are prime. 3
 5, 7, 17, 23, 31, 41, 53, 67, 71, 89, 127, 149, 173, 199, 251, 281, 283, 347, 383, 409, 461, 479, 523, 593, 641, 691, 719, 773, 823, 887, 971, 1033, 1097, 1163, 1231, 1301, 1373, 1447, 1619, 1709, 1741, 1823, 1907 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Note that p,q,r are not required to be consecutive primes. LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 EXAMPLE a(1)=5 because both 5 + 2 = 7 and 7 + 4 = 11 are prime; n=2: d=4, p=7 because both p + d = 11 and 11 + 6 = 17 are prime; n=3: d=6: primes 11,13 are not qualified while 17 + 6 = 23 and 23 + 8 = 31 are prime hence a(3)=17. MATHEMATICA m=0; p=3; s={}; Do[p = NextPrime[p]; m=m+2; While[!PrimeQ[p+m]||!PrimeQ[p+2*m+2], p=NextPrime[p]]; AppendTo[s, p], {50}]; s PROG (PARI) first(n)=my(v=vector(n), k=4); v[1]=5; forprime(p=5, , if(isprime(p+k) && isprime(p+2*k+2), v[k/2]=p; if(k==2*n, return(v)); k+=2)) \\ Charles R Greathouse IV, Mar 01 2017 CROSSREFS Cf. A283159. Sequence in context: A044966 A359297 A283159 * A191145 A145354 A214345 Adjacent sequences: A283142 A283143 A283144 * A283146 A283147 A283148 KEYWORD nonn AUTHOR Zak Seidov, Mar 01 2017 EXTENSIONS a(16)-a(17) corrected by Charles R Greathouse IV, Mar 01 2017 STATUS approved

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

Last modified May 19 05:56 EDT 2024. Contains 372666 sequences. (Running on oeis4.)