OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..250
MATHEMATICA
tctnQ[n_]:=Module[{c=1+FromDigits[9-IntegerDigits[n]]}, IntegerQ[ (Sqrt[8c+1]-1)/2]]; Select[Prime[Range[10000]], tctnQ] (* Harvey P. Dale, Sep 21 2012 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jason Earls, May 31 2003
STATUS
approved