A340821 a(n) is the least prime p such that prime(n)*p + prime(n+1)*q + prime(n+2)*r is prime where p,q,r are consecutive primes.

3, 3, 3, 61, 3, 3, 17, 3, 5, 13, 3, 29, 17, 13, 3, 5, 7, 19, 23, 5, 11, 3, 3, 23, 3, 3, 3, 19, 19, 7, 7, 23, 43, 5, 7, 67, 7, 7, 11, 19, 29, 3, 3, 7, 19, 5, 3, 3, 23, 3, 29, 7, 17, 13, 37, 13, 7, 3, 23, 3, 3, 19, 53, 29, 17, 3, 3, 43, 7, 43, 5, 11, 5, 7, 19, 19, 19, 163, 3, 3, 3, 7, 5, 31, 17, 19

Offset

2,1

Links

Robert Israel, Table of n, a(n) for n = 2..10000

Example

a(3) = 3 where 5*3 + 7*5 + 11*7 = 167 is prime.

Maple

f:= proc(n) local k, t;
  for k from 1 do
     t:=ithprime(n)*ithprime(k) + ithprime(n+1)*ithprime(k+1) + ithprime(n+2)*ithprime(k+2);
     if isprime(t) then return ithprime(k) fi;
  od
end proc:
map(f, [$2..100]);

Crossrefs

Cf. A340817.

Sequence in context: A124013 A135584 A174538 * A091323 A174641 A217671

Adjacent sequences: A340818 A340819 A340820 * A340822 A340823 A340824

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Jan 22 2021

Status

approved