A075278 Interprimes which are of the form s*prime, s=3.

6, 9, 15, 21, 39, 69, 93, 111, 129, 309, 381, 393, 453, 489, 501, 687, 723, 771, 879, 933, 939, 1011, 1167, 1299, 1527, 1563, 1569, 1839, 1941, 1983, 2157, 2217, 2229, 2271, 2391, 2463, 2661, 2811, 2859, 2913, 3039, 3099, 3189, 3453, 3459, 3651, 3849

Offset

1,1

Comments

Interprimes which are of the form s*prime are in A075277-A075296 (s = 2-21). Case s = 1 is impossible.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

39 is an interprime and 39/3 = 13 is prime.

Maple

R:= NULL: count:= 0:
p:= 1:
while count < 50 do
  p:= nextprime(p);
  if nextprime(3*p) + prevprime(3*p) = 6*p then
    R:= R, 3*p; count:= count+1
  fi
od:
R; # Robert Israel, Apr 21 2026

Mathematica

s=3; Select[Table[(Prime[n+1]+Prime[n])/2, {n, 2, 1000}], PrimeQ[ #/s]&]

Crossrefs

Cf. A075277-A075296.

Sequence in context: A168544 A001748 A097426 * A316048 A102971 A023885

Adjacent sequences: A075275 A075276 A075277 * A075279 A075280 A075281

Keyword

easy,nonn

Author

Zak Seidov, Sep 12 2002

Status

approved