cp's OEIS Frontend

A330424 a(1) = 1, a(2) = 2; thereafter a(n) = smallest number not occurring earlier such that both the sum of three successive terms and the sum of three successive digits are prime numbers.

%I A330424 #11 Jan 13 2020 09:36:12
%S A330424 1,2,4,5,8,6,3,20,14,25,44,34,49,68,32,27,24,10,67,60,12,29,26,52,
%T A330424 41065,62,50,61,40,30,43,64,72,21,46,16,41,22,38,23,28,122,7,82,18,81,
%U A330424 2012,218,21021,84,58,69,2002,90,201,106,76,47,88,128,1223,2038
%N A330424 a(1) = 1, a(2) = 2; thereafter a(n) = smallest number not occurring earlier such that both the sum of three successive terms and the sum of three successive digits are prime numbers.
%H A330424 Lars Blomberg, <a href="/A330424/b330424.txt">Table of n, a(n) for n = 1..10000</a>
%e A330424 After 8 and 6 the next term is 3 as 8+6+3 = 17 is a prime;
%e A330424 after 6 and 3 the next term is 20 as 6+3+20 = 29 and 6+3+2=11 are both primes;
%e A330424 after 3 and 20 the next term is 14 as 3+20+14 = 37 and 3+2+0=5 are both primes;
%e A330424 etc.
%Y A330424 Cf. A076990 (only the sum of three successive terms is prime).
%K A330424 base,nonn
%O A330424 1,2
%A A330424 _Eric Angelini_ and _Lars Blomberg_, Dec 14 2019