OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..565
MAPLE
N:= 10^5:
P1:= select(isprime, [seq(i, i=1..N, 4)]):
P3:= select(isprime, [seq(i, i=3..N, 4)]):
A1:= select(isprime, P1[1..-3]+P1[2..-2]+P1[3..-1]):
A3:= select(isprime, P3[1..-3]+P3[2..-2]+P3[3..-1]):
M:= min(nops(A1), nops(A3)):
sg:= [seq(signum(A1[i]-A3[i]), i=1..M)]:
select(t -> sg[t]<>sg[t-1], [$2..M]);
CROSSREFS
KEYWORD
nonn,look
AUTHOR
J. M. Bergot and Robert Israel, May 13 2018
STATUS
approved