OFFSET
1,1
COMMENTS
a(n)=3 if and only if prime(n+1) is in A106067. - Robert Israel, Jul 17 2020
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
f:= proc(n) local pn, p;
pn:= ithprime(n+1);
p:= 1;
do
p:= nextprime(p);
if isprime(2*pn+p) and isprime(p*pn+2) then return p fi
od
end proc:
map(f, [$1..100]); # Robert Israel, Jul 17 2020
MATHEMATICA
f[n_Integer/; n>1]:=Module[{p=3}, While[Or[CompositeQ[2*Prime[n]+p], CompositeQ[p*Prime[n]+2]], p=NextPrime[p]]; p]; f/@Range[2, 100]
PROG
(PARI) a(n) = my(p=2, q=prime(n+1)); while(!isprime(2*q+p) || !isprime(p*q+2), p=nextprime(p+1)); p; \\ Michel Marcus, Jun 08 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Ivan N. Ianakiev, Jun 08 2020
STATUS
approved