A356074 a(n) is the first prime that starts a sequence of exactly n consecutive primes prime(k+1), ..., prime(k+n) where prime(k+i)+2^i is prime for i = 1...n but not for i = n+1.

3, 11, 17, 5, 37307, 17387, 87020177, 1309757957

Offset

1,1

Links

Table of n, a(n) for n=1..8.

Example

a(3) = 17 is a term because 17, 19, 23 and 29 are consecutive primes and 17 + 2^1 = 19, 19 + 2^2 = 23, and 23 + 2^3 = 31 are prime but 29 + 2^4 = 45 is not prime.

Maple

f:= proc(n) local P, T, i;
  P:= [seq(ithprime(i), i=1..n+1)]:
  T:= [seq(2^i, i=1..n+1)]:
  do
    if andmap(t -> isprime(P[t]+T[t]) = evalb(t <> n+1), [$1..n+1]) then return P[1] fi;
    P:= [seq(P[i], i=2..n+1), nextprime(P[n+1])];
  od;
end proc:
map(f, [$1..7]);

Crossrefs

Sequence in context: A243770 A298701 A216911 * A351051 A154497 A322171

Adjacent sequences: A356071 A356072 A356073 * A356075 A356076 A356077

Keyword

nonn,more

Author

J. M. Bergot and Robert Israel, Jul 31 2022

Status

approved