A358047 a(1) = 2; afterwards a(n) is the least new prime such that 2*a(n-1) + a(n) is a prime.

2, 3, 5, 7, 17, 13, 11, 19, 23, 37, 29, 31, 41, 67, 47, 43, 53, 61, 59, 73, 83, 97, 89, 79, 71, 109, 113, 127, 167, 157, 107, 103, 101, 151, 131, 139, 179, 163, 137, 193, 191, 181, 239, 199, 149, 211, 197, 223, 173, 241, 227, 229, 233, 277, 257, 283, 263, 271, 269, 349, 293

Offset

1,1

Comments

Sequence is non-monotone. Are all primes in the sequence?

Links

Table of n, a(n) for n=1..61.

Mathematica

s = {n = 2}; Do [p = 3; While [MemberQ[s, p] || !PrimeQ[2*n + p], p = NextPrime[p]]; AppendTo[s, n = p]; p = NextPrime[p], {100}]; s

Prog

(PARI) lista(nn) = my(va = vector(nn), last=2); va[1] = last; for (n=2, nn, my(p=2); while(!isprime(2*last+p) || #select(x->(x==p), va), p = nextprime(p+1)); va[n] = p; last = p; ); va; \\ Michel Marcus, Nov 14 2022

Crossrefs

Sequence in context: A059471 A059496 A066814 * A072885 A178209 A360781

Adjacent sequences: A358044 A358045 A358046 * A358048 A358049 A358050

Keyword

nonn

Author

Zak Seidov, Oct 27 2022

Status

approved