A157996 Primes which are sum of 1 and two nonconsecutive primes p1 and p2, p2 - p1 > 2.
11, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283
Offset: 1
Keywords
Examples
11=3+7+1, 17=5+11+1, 19=5+13+1, ...
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Programs
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Haskell
a157996 n = a157996_list !! (n-1) a157996_list = map (+ 1) $ filter f a006093_list where f x = g $ takeWhile (< x) a065091_list where g [] = False g [_] = False g (p:ps@(_:qs)) = (x - p) `elem` qs || g ps -- Reinhard Zumkeller, Mar 12 2012 -
Mathematica
lst={};Do[p0=Prime[n];Do[px=Prime[n+k];If[PrimeQ[a=p0+px+1],AppendTo[lst,a]],{k,2,2*5!}],{n,6!}];Take[Union[lst],222] -
PARI
is(n)=if(!isprime(n),return(0)); my(p=3,q=5); forprime(r=7,n-4, if(isprime(n-1-r) && n-1-r <= p, return(1)); p=q; q=r); 0 \\ Charles R Greathouse IV, Nov 05 2015
Comments