A158350 Primes p such that previousPrime(p) + p -+ 1 are twin primes.

7, 11, 17, 23, 31, 71, 101, 127, 233, 307, 311, 409, 419, 443, 617, 647, 661, 719, 743, 811, 839, 863, 941, 1049, 1061, 1361, 1487, 1667, 1697, 1889, 2003, 2053, 2129, 2131, 2243, 2267, 2551, 2647, 2711, 2753, 2767, 2833, 3049, 3109, 3163, 3229, 3299, 3331

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Mar 16 2009

Keywords

• nonn

Comments

Sum of two consecutive primes = arithmetic mean of twin primes.

Examples

			5+7=12-+1 primes, 7+11=18-+1 primes, 13+17-+1 primes, ...
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A099349.

Programs

Maple

t1:=[]; for n from 2 to 1000 do p:=ithprime(n); q:=prevprime(p);
if isprime(p+q-1) and isprime(p+q+1) then t1:=[op(t1),p]; fi; od: t1; # N. J. A. Sloane, Dec 24 2012

Mathematica

lst={}; Do[p0=Prime[n]; p1=Prime[n+1]; a=p0+p1; If[PrimeQ[a-1] && PrimeQ[a+1], AppendTo[lst, p1]], {n, 1000}]; lst