OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..50
EXAMPLE
a(2) = 31 because 31 is prime, and is the 4th (zero-free positive) number with digital sum 4 {4,13,22,31,112,121,211,1111}.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jonathan Vos Post, Jan 25 2011
EXTENSIONS
a(13) and a(14) from Zak Seidov, Jan 26 2011
Terms a(15) onward from Max Alekseyev, Aug 19 2013
STATUS
approved