OFFSET
1,1
COMMENTS
Digits in position a(n) are prime, namely 2, 3, 5 or 7. Any step chooses the minimum integer not yet present in the sequence and not leading to a contradiction.
EXAMPLE
The sequence cannot start with 1 because the first digit, 1 itself, is not prime. Then let us put 2. The next digit must be prime: 3. Even the third must be prime: 5. No specific indications for the fourth digit. We can choose 1 because the first digit, 2, is prime. The fifth must be prime: 7. And so on.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava, Feb 15 2012
STATUS
approved