OFFSET
1,2
COMMENTS
The full sequence uses digits 4 and 7 only, except for a(1) = 1 and a(2) = 2.
LINKS
Jean-Marc Falcoz, Table of n, a(n) for n = 1..16384
FORMULA
a(n) = A284971(n-2) for n>=3. - Alois P. Heinz, Jul 15 2023
EXAMPLE
1 + 2 = 3 and there is no term or digit 3 in the sequence;
1 + 4 = 5 and there is no term or digit 5 in the sequence;
1 + 7 = 8 and there is no term or digit 8 in the sequence;
2 + 4 = 6 and there is no term or digit 6 in the sequence;
2 + 7 = 9 and there is no term or digit 9 in the sequence;
4 + 4 = 8 and there is no term or digit 8 in the sequence;
4 + 7 = 11 and there is no term 11 in the sequence;
7 + 7 = 14 and there is no term 14 in the sequence;
etc.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Apr 16 2018
STATUS
approved