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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.
1
3, 11, 17, 5, 37307, 17387, 87020177, 1309757957
OFFSET
1,1
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
KEYWORD
nonn,more
AUTHOR
J. M. Bergot and Robert Israel, Jul 31 2022
STATUS
approved