OFFSET
1,2
COMMENTS
This is the lexicographically earliest infinite sequence of distinct nonnegative terms with this property; a(1) and a(2) are the only terms containing a zero.
LINKS
Carole Dubois, Table of n, a(n) for n = 1..1342
EXAMPLE
a(20) = 19 and a(21) = 25; the digitsum of 19 is 10 and 10 is 2*5;
a(21) = 25 and a(22) = 71; the digitsum of 25 is 7 and 7 is 7*1;
a(22) = 71 and a(23) = 24; the digitsum of 71 is 8 and 8 is 2*4;
a(23) = 24 and a(25) = 23; the digitsum of 24 is 6 and 6 is 2*3; etc.
PROG
(Magma) a:=[0, 10]; for m in [3..70] do k:=1; while k in a or (IsPrime(&+Intseq(k)) and &+Intseq(k) ge 11) or &*Intseq(k) ne &+Intseq(a[m-1]) do k:=k+1; end while; Append(~a, k); end for; a; // Marius A. Burtea, Oct 16 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Oct 02 2020
STATUS
approved