OFFSET
1,2
EXAMPLE
a(4) =761995= 1234*1235/2
MATHEMATICA
tno[lst_]:=Module[{n=FromDigits[lst]}, (n(n+1))/2]; tno/@Table[Flatten[ IntegerDigits/@Range[n]], {n, 20}] (* Harvey P. Dale, Aug 16 2011 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 18 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 07 2003
STATUS
approved