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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.
2
1, 2, 4, 5, 8, 6, 3, 20, 14, 25, 44, 34, 49, 68, 32, 27, 24, 10, 67, 60, 12, 29, 26, 52, 41065, 62, 50, 61, 40, 30, 43, 64, 72, 21, 46, 16, 41, 22, 38, 23, 28, 122, 7, 82, 18, 81, 2012, 218, 21021, 84, 58, 69, 2002, 90, 201, 106, 76, 47, 88, 128, 1223, 2038
OFFSET
1,2
LINKS
EXAMPLE
After 8 and 6 the next term is 3 as 8+6+3 = 17 is a prime;
after 6 and 3 the next term is 20 as 6+3+20 = 29 and 6+3+2=11 are both primes;
after 3 and 20 the next term is 14 as 3+20+14 = 37 and 3+2+0=5 are both primes;
etc.
CROSSREFS
Cf. A076990 (only the sum of three successive terms is prime).
Sequence in context: A352808 A076990 A330434 * A057168 A087711 A123128
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Lars Blomberg, Dec 14 2019
STATUS
approved