OFFSET
1,1
EXAMPLE
a(9) = 34567 because it is semiprime 13 * 2659, and (3,4,5,6,7) are consecutive ascending digits.
MAPLE
R:= 4, 6, 9: V:= [$1..9]:
for d from 2 to 50 do
V:= map(n -> 10*n + ((n+1) mod 10), V);
W:= select(t -> numtheory:-bigomega(t)=2, V);
R:= R, op(W);
od:
R; # Robert Israel, Nov 15 2023
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jonathan Vos Post, Aug 12 2012
EXTENSIONS
Corrected and extended by R. J. Mathar, Aug 13 2012
STATUS
approved